Boyons are yellow, gelatinous creatures that only appear in Super Metroid. They appear to be made of an extremely resilient mucus-like substance, as it takes numerous Bombs, Super Missiles or Power Bombs to kill them. No other weapons are capable of harming the organisms. They will rest quietly at the bottom of a small hole until something approaches. At that point, they will repeatedly bounce up from their hole until the offending creature leaves. In one instance, Samus freezes several Boyons to "fill in" several gaps in the floor so she can dash across it and Shinespark.
The Space Pirate leader Draygon spits out projectiles that look like gray Boyons. These projectiles do not harm Samus; instead, they cling to her and decrease her mobility enough for Draygon to grab her. If Samus uses the secret Grappling Beam method of killing the creature, the mucus projectiles can also be Draygon's undoing.
Boyons greatly resemble the X Parasites seen in Metroid Fusion, though the former are not translucent and do not contain glowing nuclei in their centers. When active, Boyons have many thin pseudopods stretching out from the main body constantly, unlike the X who have few, but thick, pseudopods. In beta trailers for Fusion, the sprites used for the X are Boyon sprites, recolored purple.
"Freeze them in place with the Ice Beam."