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.
No other Pokémon have the same Egg Group combination as Ferroseed and its evolved form.
Ferroseed has the lowest base Speed stat of all Steel-type-type Pokémon.
It also ties with Gossifleur for the lowest base Speed stat of all Grass-type Pokémon.
It also has the lowest base Special Attack stat of any Grass-type Pokémon.
From Generation VI onward, Ferroseed's Hidden Ability is the same as its first Ability, Iron Barbs, unlike its evolved form, which has a different Hidden Ability, Anticipation. A Ferroseed with Iron Barbs as its Hidden Ability can evolve into an Anticipation Ferrothorn and can be bred to produce more Ferroseed with Iron Barbs as their Hidden Ability.