@kimberly-huber, @egardner It may be a pecten fragment although the photo gives me the impression it may be a thicker shell of some other ridged type. You might try asking @cferrara or @lcone. These guys are more in tune with these more recent shells.
I think that a shell fragment would be a good guess. Pectin material is abundant in the Aurora material, and tiny fragments are in every shovelful, especially in the high pressure washed reject material, which has been blasted by the hoses. That is the material that is in the reject piles at the museum.