The Blastcap is a creature native to Tallon IV. Blastcaps are weeds that often grow in small clusters and will rattle in warning when anything approaches. The fungal cap, which is filled with toxins, will detonate if Samus comes in contact with it, or if she fires upon it repeatedly. The resulting explosion and venomous fumes will cause damage. Even the flesh of the weed itself is poisonous, keeping it from being eaten by indigenous lifeforms.
- "Volatile chemicals within this weed's toxic fungal cap may explode if agitated. The poisonous flesh of the Blastcap helps keep it from being eaten. It also detonates its fungal cap when it senses even slight contact." —Metroid Prime Logbook "Blastcap" (Metroid Prime)
- "A large mushroom that explodes on contact, emitting noxious gas. Originating on Tallon IV, its spores can survive without atmosphere and have propagated throughout the galaxy on solar winds." —Metroid Prime Hunters Logbook "Blastcap" (Metroid Prime Hunters)