It looks like a beetle that a superworm would have turned into. Perhaps you let a superworm in your cham's cage, and it made it to safety? It's happened with me before, when a superworm found its way into a crevice in bamboo, I just thought what ever
If you leave a superworm in a container by itself it will eventually stress it out enough to force it to pupate and turn into a beetle, then you could breed them.