Oceanic Fossil Identification

[Aaron McKay]

I discovered this fossil very near the summit of a 8,500 foot (2,600 meter) peak in southern Idaho.  It was within a dark band of strata and there were various coral/shell fossils found in the same strata (see last photo).  Amazing to me that the seafloor is now hoisted to the top of a mountain peak!  I can't tell what this particular fossil is, though I immediately thought bone given the structure when I picked it up.  My 8 year old is confident it is a T-Rex, but given it is near oceanic fossils, I'm doubtful.  The fossil is broken and seems to be sliced in half vertically, exposing the inner part of the fossil.  The ends of the fossil is also missing so hard to tell how long this could have been.  Notice some bumps/ripples on the backside of he fossil (photo 6).  Could this be orthoceras or something similar?

Edited April 13, 2021 by Aaron McKay
Additional clarity

[Myrmica]

Hello Aaron,

  You may have a sort of a primitive calcareous sponge called an or aulacerid.  Google that to see some images.  The other specimens are various corals.  

[Aaron McKay]

Thanks Myrmica!  I hadn't thought of a primitive sponge.  These fossils were practically falling out of the strata with many more easily visible.  I can't wait to visit again when I am next in Southern Idaho.  Do you think that strata with these kinds of fossils possibly could also hold larger vertebrate fossils?