Mimic is a scrapped Monster from My Singing Monsters, it does has a description, however:
"The Mimic monster is an extremely unique monster among the rabble. They have three legs and they are surrounded by mysterious atmosphere. They contain luminous substance, so when they is danger, those substance lightens up to protect Mimic."
-in game files.
This Monster was first shown in Big Blue Bubble's Extra Life 2018 Event on Twitch. It was said to be a scrapped Quint Element. The design appears to be a 3-legged parrot. Part of the design of the Monster was, however, reincorporated as Rare Clamble. It was scrapped because the developers didn't think it was good enough for the game. The mechanics of the Monster was that the player could make its sound, a feature which was tweaked and turned into the Recording Studio.
- In the files, it refers to Mimic as "Secret Quint Element".