Meet Mycota.

Its form changes depending on what it wants to be, or its emotions. For examples, if it's angry, the head will become a destroying angel. If it's sad, it will become an indigo milk cap and so forth. However, it can change its head into whatever it wants whenever it wants.

As for the body, it will almost always be that of an ungulate. The most used forms are that of a moose and a kiang, as well as, sometimes, a deer or an elk.

It feeds by growing mycelia from its "hooves" and taps into the mycelium of other fungus. It can only feed on the same type of fungus as its head is at the time.

The top left is a white tailed deer/destroying angel. Top right is a kiang/indigo milk cap. Middle, white tailed deer/king bolete. Bottom left (feeding) white tailed deer/king bolete and bottom middle is moose/ganoderma fungus with cockscomb coral fungus as "antlers".

:D