microscopic penta- or hexagonal structure in rock

[anonaddict]

location: aarhus, denmark

found: loose beach rock

units: metric

my ID: best guess is tabulate coral

observations: under the microscope the best way i can describe it is a geometric pattern resembling honeycomb, but its too small to see the exact shape its also possible its circular. the shapes are hollow and seem to be hollow the whole way down, parallel to the normal vector of the riccola plane but i dont have any objects that would fit since their diameter is ~0.2 mm

 

 

ive tried taking a picture but its not good

 

 

 

it looks like tabulate coral but im unsure if that is accurate since the other surfaces are all rough

 

 

[Fossildude19]

Could be a bryozoan.

[anonaddict]

11 hours ago, Fossildude19 said:

Could be a bryozoan.

i usually associate those with the large calcium(?) nets they build, and my associated internet searches have successfully made me more confused. it's very unclear to me what bryozoans even are or what their fossils look like. many fossils have very distinct characteristics like ammonites or sea urchins but i cant even figure out what bryozoans really are.

 

My understanding is they are tiny (~mm scale) animals living in colonies and constucting that iconic net or tree (CS, not biology) shaped skeleton they live inside? however it seems they have very complex behaviors and can even make floating colonies and from drawins i cant figure out which parts are animals, colonies of animals, or structure. some of them look like fish(???) or slugs

 

(image Ernst Haeckel 1904 • Public domain taken from wikipedia)

 

could you elaborate on your thought process on why you believe it could be a bryozoan, and possibly which part of it you're associating it with?

[Fossildude19]

Small holes in large numbers are usually indicative (to me) of zooecia of bryozoans.

 

I also would not rule out sponge, however.   Or something geologic in nature.

Not really my area of study or expertise.

 

Bryozoans can be encrusting, or they could be branching.  They are tiny filter feeders that poke out of the zooecia to feed.

 

 

 

Corals usually show some sort of structures to them:

 

 

 

 

As stated, this was just a guess on my part, but I could be wrong.

The sixth photo looks like an encrusting bryozoan, to me. 

 

 

 

 

 

 

This photo appears to show some recent annelid worm borings from something like Polydora.

 

[Rockwood]

This looks more like a Tubuliporid to me.

[Fossildude19]

7 minutes ago, Rockwood said:

This looks more like a Tubuliporid to me.

 

You might expound on this some.  Tubuliporids are bryozoans, correct?

The examples I looked at seem much more tubular, and singular in line, to me. 

[Rockwood]

wiki has a good illustration of the general form. I have some in my collection that look like the end of a tiny bundle of straws.