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. It 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. It absorbs minerals from rocks.
Ferroseed and its evolution have the fewest weaknesses of all Grass-type Pokémon.
No other Pokémon have the same Egg Group combination as Ferroseed and its evolved form.
Ferroseed is both the slowest Grass-type Pokémon and the slowest Steel-type Pokémon.
In Generation VI games, Ferroseed's Hidden Ability is same as its first Ability, Iron Barbs, unlike its evolution which has different Hidden Ability Anticipation. A Ferroseed which will evolve into a Ferrothorn with Anticipation can be bred to produce Ferroseed that will evolve into a Ferrothorn with Anticipation.
This means that in Generation VI, Ferroseed is the only unevolved Pokémon without a Hidden Ability that evolves into a Pokémon with a Hidden Ability.