Cactus

Cactus is a Test in Lab Experiment. It is slightly a harmful test, causing a player to deal some damage upon contact with it. In some cases, such as the Sudden Death Game Setting, it can actually be beneficial. It is possible for players to stand on a cactus without taking damage, in the same vein as standing on Poison without moving. This rule only applies while:
# The cactus isn't moving. (i.e. it isn't on a elevating, spinning, flipping, translating, rising, or stretching plate)
# The player isn't moving.
and because of this, it can act as a slightly raised platform and when lava gets near, keeping the player alive for an extra 10-15 seconds. A certain position must be achieved so that the player's idle animations do not cause additional damage to be taken. These positions can be hard to find, but keeping on leg off of the edge is a common tactic for finding one. If you die from a cactus, you will claim the "Cactus Hug." badge.
Cactus also has it's own Game setting named Desert, in which every plate is affected by two Tests automatically: Cactus, and Desert.Category:Tests