This is Holden.. He's a mimic. In my stuff, a mimic is a creature that looks like an animal with an egg-shaped body that has a big lock on the front of the belly, with a unique key that can't be imitated, and they open by a hinge on the back. A mimic feels hungry or sated according to how much their contents are valued by others, so they are often ambitious, but sometimes resort to thievery.

It goes without saying that the name comes from their ability to disguise themselves as containers. However, all mimics have tails, which they cannot hide when transformed. The transformation to and from their true forms and their disguises can be forced as a reflex by pulling the tail, or, if the mimic is disguised, attempting to open the container they are posed as.