This is a bivalvia, i.e. a bi-valve shell. It is rare to find muscle tissue fossilized. However, this appears to be the adductor muscle in this bi-valve shell. This is a rare find, found by PMNS Curator T. W. Proctor, J.D. in March, 1999. It was identified by Terry himself and this identification could be in error, but remains his identification, until proven wrong.