Talk:Rockgrub/@comment-35507650-20180506120315/@comment-35507650-20180507003532

There are a few problems with this reasoning. If there's an internal skeleton, as Specimen Theta possesses, then the exterior shell is osteodermic plating, not an exoskeleton. Internal skeletons and exoskeletons are mutually exclusive by concept.

Also, the PDA says it shares skeletal traits in common, noting the external shell and 4 eye sockets. It would be a mistake to assume this means they're related or in any way the same, given that's a very Linnean method of cladistics and not a genetic phylogenic process.