From Sonic Retro
The Mogu is robotic mole badnik found in Secret Base Zone, Egg Rocket Zone, and Cosmic Angel Zone. Lacking any offensive capability, these guys simply pop out of holes in the ground (like the Madmole), attempting to hurt the player when walked straight into. When they pop out, either perform a spin jump or a spin attack to destroy them. They bear a slight resemblance to Burrobot from Sonic 1 & Grounder from Sonic 2.