Tosenbo

Tōsenbo are spiked, slug-like creatures from the star stage of the Space Zone in Super Mario Land 2: 6 Golden Coins. These creatures inflate and deflate at a regular interval, but are barely visible when they are not inflated. They are invulnerable when not inflated, so Mario should stay away from them; they can only be defeated using a Star or a fireball when they are in their inflated state. According to the Shogakukan guide, they may related to Unibō.