This species is rare on Sanibel. I think that some valves came in with beach replenishment sand.

I found the first one of these a number of years ago and took it to the museum. But at first José Leal, the curator of the Bailey Matthews National Shell Museum, was not sure that this was a genuine occurrence, so he waited until someone else found one before he accepted the species onto his excellent photo-illustrated database here:

https://www.shellmuseum.org/southwest-florida-shells