The biggest one has been around for as long as you remember, encased in that glass-like material. You've considered giving it a name, but it always struck you as a little morbid to name a dead cat.
The others were the result of a few experimental mishaps before you got the hang of the ECTOBIOLOGY equipment. You keep them around to remind you of the perils of the inexact science, and also because they're weird looking and cute. You've since cloned many healthy felines, but they all live in the LABORATORY out back. Your pet CAT doesn't really get along with other cats, and you don't want to upset him.