We have a late “What Is It Wednesday” entry this week, but this time we’re seeking your help. We’re not certain what we’re looking at this time.
These specimens were recovered from the Chesapeake Bay area in 1994 by Laurie Anderson. They’re from the Rushmore Member of the Yorktown Formation, a Pliocene marine unit.
The largest are approximately 14.0 mm in length. They’re boomerang-shaped overall, but cup inward on the concave side. They resemble tiny jai alai cestas.
They appear to have grown concentrically as there are apparant growth lines on the convex surface.
If you’ve seen something like this before or know what they are, please comment, as we’re stumped.