Skipsqueak

Skipsqueaks are mouse-like enemies that appear in Super Mario 3D World. Their name is a portmanteau of "skip" and "pipsqueak".

Super Mario 3D World
Skipsqueaks constantly jog on moving platforms going in the opposite direction, causing them to remain in one place. They also jump up periodically and are usually found in groups of two or more. Skipsqueaks can be defeated by using any form of attack, including a jump attack. They appear in the levels Really Rolling Hills, Grumblump Inferno, and Rainbow Run.

There is a variation of this enemy known as Spiny Skipsqueaks which appear in Cookie Cogworks and Rainbow Run.

Super Mario Maker 2
Skipsqueaks and Spiny Skipsqueaks reappear as enemies that can be placed in Super Mario Maker 2 stages. Skipsqueaks jump whenever Mario jumps, and are not affected by Conveyor Belts.