It is bound and cannot be traded in the trading market. You can open

tet eggs

to obtain pets with ABCD levels.

There are four kinds of pets in Food vs. Mouse, the fourth one is D-level

Bubble Bobble

, which is equal to a single layer

Xiaolongbao

. The third type is C-level

The Wizard of Oz

, which is equivalent to a double-layered steamed bun. The second type is the B-level Poseidon Prince, which is equivalent to a third-line wine rack. The first is the A-level Fury of Fire, which is equivalent to the egg cooker pitcher.