Muncher

Munchers are a subspecies of Piranha Plant that have appeared in numerous Super Mario titles, beginning with Super Mario Bros. 3. These plants appear in various stages and are immobile, but are also completely indestructible. Functioning as more of an obstacle than an enemy, Munchers constantly snap their mouths and devour whatever falls upon them. Mario can do nothing to destroy Munchers as Fire Flowers and even Power Stars have no effect, although Mario can walk along a field of Munchers while the Power Star makes him invincible. While typical items have no effect on Munchers, P Switches can turn them into coins, allowing Mario to collect them.