It resembles some sort of cross between a conifer cone and an egg; though in a vaguely round shape, it is covered in hard plates of what looks to be thick tree bark. Trying to peel the bark off only results in the plates locking down more tightly.
It turns out that the pinecone-egg was actually a small mammal, tightly curled up. The plates are part of a shell on its back that grows more slowly than the creature itself; soon, the armor that covers it may only plate its back. It seems to be growing antlers, and is afraid of anything larger than it; this means its handler, as well. It quickly curls up when threatened, but perhaps it can be trained to recognize its handler and accept hand-fed leaves.