similar to sliced bone filled with a something else, but obviously not

[Adam Hess]

On my way home from my parents in Goodhue county MN, I stopped at a roadcut. Bottom 20ft were a well sorted coarse sandstone (all grains were similar in size but large, and it was pretty soft). Above that was a very yellow sandstone (non-fossiliferous). Most things in this area are roughly Ordivician. Everything above went away with the glaciers.

Anyways, washed down from the top, I found several white rocks that were reminiscent of cuttings of long bones. They were filled with some other mineral (kinda like marrow).

 

I know they can't actually be fossils, since bones didn't even exist 450 million years ago. Just curious if anyone has an idea what sort of process might've made these? These were the only whitish rocks, and all of them were filled with the other mineral.

 

Thanks

[Fossildude19]

These look like chert nodules,  (Nodular Chert) which can form in many weird shapes.