Buzzy Beetle

From Mariopedia

Buzzy Beetles are blue shelled, tortoised-like creatures commonly found in underground locations, such as caverns and ruins. Buzzy Beetles first appear in Super Mario Bros. as infrequently encountered enemies. Due to their powerful shells, Buzzy Beetles are largely immune to most forms of attacks; originally depicted as attacking players by simply walking into them, later games would introduce other attack patterns for Buzzy Beetles, such as dropping from the ceiling and retracting into their shells and spinning into characters. Various Mario RPGs describe Buzzy Beetle as both cute and temperamental. Aside from making a small appearance in the Japan-exclusive anime Super Mario Bros.: Peach-Hime Kyushutsu Dai Sakusen!, Buzzy Beetles have been relatively obscure in mediums outside the video games.