The "gladiator glove" theory sounds plausible enough.  Still, I suspect
Linnaeus must have questioned the collectors in an effort to find out more
about the habits of the species?  He must have gotten some verbal information
- how else could he know that Cypraea moneta was used as money, for example?
To the question of other Linnaean names based on behavior, how about Cypraea
clandestina (secretive); Cypraea errones (wandering); and Cypraea staphylaea
(could refer to the individual grape-like appearance of a single shell, but I
believe it refers to the tendency of the species to aggregate in "grape-like"
clusters).
As for Crepidula fornicata - what a let-down, if it really is named for the
shape of its shell!  All my dirty stories - with no real basis in fact!  This
species however, I have observed in nature many times; and its tendency to
form tall stacks, with a few females on the bottom and several males on top
kind of begs the other interpretation of the name!  And, Linnaeus had the
opportunity to see this species first hand; that, plus his readiness to name
species after anatomical parts and bodily functions supports the more lurid
interpretation of the name, I think.  If it's really fornix, so be it, but I
still lean toward gastropod promiscuity
 
Paul M.