Gastropod id?

[Natali]

Found at fossil & prairie park in Rockford, IA. Any ideas about a species? Also am I correct that it looks like a coral or maybe an encrusting sponge was growing on top of it? Thanks in advance.

[fifbrindacier]

Check this post, there are some internal casts of gastropods that look like yours (i'm not saying they are the same).

On 11/26/2020 at 10:52 PM, DavidA said:

Found this fossil recently while visiting the Fossil Park near Rockford, Iowa. The fossils here are Devonian in age, and belong to the Hackberry Group/Lime Creek Formation. Have found numerous varieties of brachiopods, horn and colony coral, gastropods, bryozoa, and pieces of crinoid stems, but have never seen anything quite like this. Since it was such a crappy day, I had the whole park to myself except for one guy from Minnesota. Thinking he might be more knowledgeable than myself, I asked for his opinion on what he thought this was. He suggested it was definitely a crinoid calyx. I am not so sure.

Thank you all for checking it out.

 

 

[ClearLake]

Based on its size and general shape, it could be one of the species of Floydia.  But it is hard for me to be very certain given that it is primarily a cast and I'm having trouble seeing the folds/wrinkles that are diagnostic of the genus.  Perhaps someone else more familiar with the fossils from there will have a more definitive ID for you.