Ferroseed is a cave-dwelling Pokémon resembling a durian. It has many green thorns around its body that are used for protection. It has a metallic body with band-like stripes, along with small yellow eyes with black pupils.
Ferroseed can stick its spikes into cave walls to absorb the minerals from the rocks. If threatened, it can shoot a barrage of spikes so it can escape by rolling away. Ferroseed's aim at throwing spikes will not be good at first, requiring practice to improve it. Ferroseed prefer living in moss caves. It absorbs minerals from rocks. As seen in the anime, Ferroseed can absorb nutrients from rocks and use them to grow moss for oxygen; different rocks create different types of moss with a variety of effects. Notably its spikes can grow big and strong from consuming the moss. However, absorbing nutrients from rocks that come from Chargestone Cave yields disastrous results.