Unidentified Life Form 40 is a form of plant encountered only once in Metroid Prime 3: Corruption. It is found in the Main Lift on Bryyo in the Bryyo Fire region, in an area only accessible while using the Morph Ball. This plant contains leafs thick enough to block the Morph Ball from accessing a tunnel, but these can easily be dealt with by destroying them with a Bomb. However, ULF 40 has the remarkable and unique ability to quickly regenerate its leaves from the roots hidden underground in a matter of seconds. This trait is inconvenient for Samus Aran, as she needs to be carried by Snatchers to reach ULF 40 which in turn blocks access to a Missile Expansion; if she fails to successfully enter the tunnel after bombing both creatures, the leaves will have grown back by the time she is levitated there again by the Snatchers. This can be avoided by simply using Snatchers to levitate to an even higher ledge, which allows Samus to drop down onto the part of the tunnel behind ULF 40, so she can reach the Missile Expansion and simply Bomb ULF 40 once to roll back down to the bottom of the room.
- Plants vaguely resembling ULF 40 can be seen in the background of certain Maridia rooms in Super Metroid.