According to the scientific definition of a species (as is currently
understood) two different species are not supposed to be able to reproduce
fertile offspring. However, two seperate species are able to reproduce
sterile offspring. Ex. a mule is a hybrid of a horse and a donkey. Two
mules cannot produce a mule. They cannot reproduce at all. They are sterile.
The only way to produce a mule is to mate a horse and a donkey. The same
applies to hybrids in Cypraeidae or any other mollusk. They may produce
offspring which is sterile, but by definition hybrids themselves cannot
reproduce.
Doug Shelton
Alabama Malacological Research Center
2370-G Hillcrest Road #236
Mobile, AL 36695