Appearing in groups, these creatures slowly spin and float around a room, only moving in 45° diagonal directions. They bounce off solid terrain. The Spiru looks like a yellow spiral, with multiple segments.
When corrupted, Spiru move at 1/2 speed. They can destroy certain blocks which can only also be destroyed by corrupted Giant Diatoms, Corrupted Laser Urchins, corrupted Giant Boulderbacks, corrupted Giant Greenworms, and the Red Coat.