Pinhead

Pinheads are a type of creature appearing in the game, Super Mario Galaxy 2. They appear as bowling pin-shaped enemies with two beady eyes and a yellow antenna. These creatures are very rare, only appearing in two galaxies: Boulder Bowl Galaxy and Melty Monster Galaxy. They can only be defeated by Rock Mario, and when they see the plumber turning into a rolling boulder, they tremble desperately.

Trivia
Similar enemies that look like flamingos appear in Wonky Circus in Wario World.