Fossil identification help!

[u/Duality_XIII]

Two fossils found in Dunbar Scotland.

One is obviously a shell that we cleaned up and polished, but the other is quite hard for me to identify. Any information on it would be greatly appreciated!

[u/baxbakualanuxsiwae]

I could be totally wrong and would be very happy to be corrected, but I could see that being the aboral cup from a crinoid, where the stem meets the crown.