Bruclarkia columbiana or Solenosteira macrospira or ?

[OregonFossil]

As I am working my way through the Keasey fm. rocks looking for fossils, I was gathering up the shards and small pieces and I notice a small piece of shell in the deep water piece I was working. Kept it just to check it out. as you can see the gastropod (I think, closest shells  with the ribbing and rings are Bruclarkia columbiana and Solenosteira macrospira (does not seem to have been found in the Keasey Fm.)) The rest of the matrix is very hard and the dental picks won't scratch what is left. I think the center shows this is definitely a Gastropod but only a partial shell and one that is really small. Know this is not much to go on but anyone want to take a guess as to what it is? The shell is very small, 2mm at most across and the top is missing but there maybe more bottom of the shell in the very hard matrix. Took a while to get it out of the 10 x 6mm sliver it was encased in.