Mecha-Bu
From Sonic Retro
Mecha-Bu (メカブ) is a badnik featured in Sonic CD, in Metallic Madness Zone.
Resembling a Japanese rhino beetle, these guys roll back and forth, raising and lowering the buzz-saw connected to their helmets. They do not turn around. When broken down due to age, these badniks cannot lift their buzz-saws.
PC Manual Description
The Robot Beetle moves around brandishing its horn with integral circular saw at enemies!