Sea Scorpions?

[Odd Rocks]

Found these softball-sized rocks in a small creek at 800’ elev in southern Indiana.  There are no exposed layers and these were found about 100’ below and downstream from a deposit of glacial till. Sorry, can’t give more help on the layer.

When I pulled them out of the water, the rocks had these small bits attached but I wiped most away before I realized they were fossils in situ.  I saved some and got these pics (sorry about the poor quality, I’m still learning how to light and shoot).  They measure 1/2 “ in length.

My guess is Eurypterids because of the segmented bodies and two paddle-like appendages near the head.  There’s one photo where I caught the front of the critter and you can see the mouth opening.  Look at the bottom of the pic.

 

If you have any tips for how to light and background specimens for photographing, please point me in the right direction.

 

 

Edited June 26 by Odd Rocks

[Thomas.Dodson]

Not fossils but the aquatic insects known as caddisflies (Trichopterans) and the cases they create.

[Odd Rocks]

And these are the shells left behind after the larvae stage?  Guess that mouth opening isn’t a mouth after all.

Thank you Thomas.

[Fossildude19]

They secrete a glue that sticks a bunch of pebbles, rocks and sand together, during their larval stage.
It protects their soft bodies.

[Odd Rocks]

I just read that at least one jewelers maker uses bits of precious materials in a closed tank to get these critters to build shells for jewelry.

 

 

 

[Odd Rocks]

I’m going to go out on a noob limb, but are y’all sure these are caddisfly larvae?   I started wondering how caddisfly larvae could stay attached to a rock submerged in a moving creek.  I also looked more closely at pictures of caddisfly larvae and they are all hollow tubes closed on one end, and a tad longer than the 1.5 centimeters that these specimens are.

 

I looked more closely at the parent rocks and noticed that there were quite a few more “caddisfly larvae” seemingly coming out of a matrix.  A closer inspection of one of the single “caddisfly larvae” I photographed for my original post revealed a solid body, and not a hollow one.  If there was a hollow cavity, it was impacted long ago.

 

The resemblance to caddisfly larvae is remarkable, and maybe these larval exoskeletons were manufactured in the parent rock’s crevices before the rock entered the water.  Maybe they survived on the rock despite the flowing water and sand particles filled the hollow tube.  However, it looks like some of the critters are still embedded in the parent rock, and they don’t look hollow.  Also, caddisfly larval tubes wouldn’t have lobed appendages or mouths.

 

Are you sure these aren’t fossils suspended in a rock matrix which was eroded away by moving water?

 

In the pictures below, the yellow lines are used to outline the shape of the specimen within the rock matrix.  The red lines highlight the lobed appendages and the red arrows point to the rear and front (mouth) of the in situ critter.  I’m also reposting two previous photos showing the impacted/solid bodies and the mouth.

 

Please take this as noobie curiosity and not a critical comment or desire to be right.

 

 

 

Edited June 27 by Odd Rocks

[Rockwood]

Cadis fly larvae are quite capable of attaching to rocks in moving water. Thier casings are relatively fragile though. I think trace fossils showing the method of construction are known. 

If these are solid there is a chance that they are fossils weathering from the rock, but I'm not sure the photos show that conclusively.

[Odd Rocks]

These were submerged in the creek.

What would I need to do to show that they are solid?  Better pics?  Breaking one in half?

Could they be an older version of Trichopterans?

[Rockwood]

17 minutes ago, Odd Rocks said:

These were submerged in the creek.

What would I need to do to show that they are solid?  Better pics?  Breaking one in half?

Could they be an older version of Trichopterans?

Just testing how easy they are to break and inspecting the ends when they do would be a start. Modern ones that are fresh should crush fairly easily. If they are filled with sediment, it should easily wash away. Finding one embedded in rock would be the gold standard though. 

[Mahnmut]

Hi,

I agree with caddisfly larvae, either empty hulls or dried out dead ones,

The second to last pic seems to show another recent animal, similar to a woodlouse/isopod?.

As far as I can see from the pics, what you marked as lobes could be bigger grains built into the hull.

The different types of caddisfly larvae are more or less "tidy". In our garden pond there is a kind that uses plant debris, in  rapid creeks I have seen very smooth mosaic like tubes, but also tubes that where cobbled together more irregularly. I do not know if the latter difference is specific to a species or more dependent on the available material, probably both.

Of course those tubes have a chance of fossilizing, being built of stone to begin with. But they also make good pseudofossils when simply dried out.

I am curious to see what your tests show.

Best regards,

J

[Fishkeeper]

I'm rather interested in that woodlouse-shaped animal. It does appear to be a modern animal, probably alive (and likely in need of being returned to its home), and I know I've seen the like of it before- but I can't seem to recall what it was. Some form of aquatic larva, if I remember right. Or it could simply be a woodlouse, possibly an aquatic one. If you'd found it near saltwater, I would think it might be a chiton, which is a gastropod that's essentially a snail in a very durable woodlouse's shell, but those are marine.

 

Edit: aha! Thanks to this article, https://georgesriver.org.au/learn-about-the-river/meet-the-waterbugs, I've been reminded that the bug I was thinking of was a water penny beetle larva. The lack of visible legs on your creature suggests to me that it might be one of those. Whatever it is, if it's still alive, it should either be returned to its habitat or killed now (a quick crush on a hard surface is generally fast and humane) so it doesn't have to die slowly of being in improper conditions.

Edited June 28 by Fishkeeper

[TRexEliot]

23 hours ago, Odd Rocks said:

I’m going to go out on a noob limb, but are y’all sure these are caddisfly larvae?   I started wondering how caddisfly larvae could stay attached to a rock submerged in a moving creek.  I also looked more closely at pictures of caddisfly larvae and they are all hollow tubes closed on one end, and a tad longer than the 1.5 centimeters that these specimens are.

 

I looked more closely at the parent rocks and noticed that there were quite a few more “caddisfly larvae” seemingly coming out of a matrix.  A closer inspection of one of the single “caddisfly larvae” I photographed for my original post revealed a solid body, and not a hollow one.  If there was a hollow cavity, it was impacted long ago.

 

The resemblance to caddisfly larvae is remarkable, and maybe these larval exoskeletons were manufactured in the parent rock’s crevices before the rock entered the water.  Maybe they survived on the rock despite the flowing water and sand particles filled the hollow tube.  However, it looks like some of the critters are still embedded in the parent rock, and they don’t look hollow.  Also, caddisfly larval tubes wouldn’t have lobed appendages or mouths.

 

Are you sure these aren’t fossils suspended in a rock matrix which was eroded away by moving water?

 

In the pictures below, the yellow lines are used to outline the shape of the specimen within the rock matrix.  The red lines highlight the lobed appendages and the red arrows point to the rear and front (mouth) of the in situ critter.  I’m also reposting two previous photos showing the impacted/solid bodies and the mouth.

 

Please take this as noobie curiosity and not a critical comment or desire to be right.

 

 

 

Former fly fishing guide here. I can 1000% guarantee these are caddis fly cases. Well, except for the one in the second to last picture, which looks like a pill bug or something.