Pestnut

Pestnuts are small, round, plant-like enemies found in Chucklehuck Woods in the game Mario & Luigi: Superstar Saga. They camouflage themselves as brown Chuckola Fruit before dropping from their trees and attacking passersby. Pestnuts are covered in green spikes, making them impossible to Jump on unless one is wearing any of the "Spiny-Killer Jump" Badges. The spiky creatures can attack by rolling into their target from the front or behind. A stronger variety with purple spikes can be found on the Seabed of Oho Ocean. In both forms, after the Pestnut takes enough damage, the spikes fall out, revealing a Beanie or Gold Beanie underneath. However, in the Oho Ocean variety, the Beanie will merely float up to the surface, eliminating the need to fight it.

Trivia

 * Pestnut is a portmanteau of "chestnut" and "pest"
 * Pestnuts appear to be Beanies in a spiky shell, or are a different species of Beanies.