(Whoops! I broke the teeth off in trying to open the valves).
Hi David,
I think the above statement provides the answer to the question. Only a
Spondylus hinge would have such interlocking teeth, preventing the shell
valves from being separated, except by breaking the hinge. If it were
not for that fact, there are a couple of other species I might suggest,
such as Hyotissa hyotis. But a hinge like that says SPONDYLUS! A few
Spondylus species are virtually spineless, and even other species may
become spineless through erosion. The specimen you described sounds
pretty eroded.
Regards,
Paul M.