The rubber sheet is a highly advanced piece of rubber, capable of bouncing the player, much like a real trampoline.
When jumped on, it will bounce the player acording to how high they fell. If the player fell from 11 blocks or under, they will not recieve any fall damage. The sheet must be connected on at least two sides to a block on the same level as it, and have a gap under it.(Note: The bouncing effect of the rubber sheet only works when the block under it is empty.)