Weird Coral-like Thingmobobs

[Bone Daddy]

Over time, I have run across some oddball stuff in the Peace River (Florida). Does anyone have any idea what these are? Are they fossil corals? Or some kind of tubeworm casts? Or something else entirely different? 

 

The larger one is singular, but I have found several of those smaller ones.

 

 

 

[caldigger]

Look like burrow casts to me.

[FossilGuy1024]

Burrow cast was the first thing that came to mind when I saw your second specimen, but the first one is something else. Sponge maybe?

[Harry Pristis]

I've puzzled over these things for years.  I currently believe that there are two type: one seems to be a cast of fine-grain sand; the other seems to be a calcareous skeleton (or an extremely good cast). 

 

The origin may be varied as well.  I originally thought these were in-filled burrows (fodichnia) or casts of a branching bryozoan.  The invert. guy at the FSM thought they were probably casts of hydrozoans.  I now believe that all of these origins are possible

 

Note that the original entity has grown around a tube worm shell; therefor, it's not a cast, but is a skeleton.  The side-by-side specimen in the image is, I have argued in another thread, an in-filled feeding burrow.

[Bone Daddy]

The larger one I have is very smooth without any discernible surface texture, but this might be the result of river action. The smaller ones have a more complex branching habit. Every time I run across one, I pick it up. I have a few more I will dig out tomorrow and share some photos of them. If the nature of these is still unknown or under debate, then maybe these can be of use to the science in some way.  

 

[Harry Pristis]

Well, your additional examples are of interest to me, but not so much to the Museum.  Under magnification, you can sort your specimens into casts and skeletons.  Maybe you'll have a specimen that will support speculation about origins.