The smallest matter in the universe was discovered by Professor Hubert J. Farnsworth in the episode Reincarnation. It was on a snail on a frog on a log in the bottom of the sea. After this discovery, Farnsworth was depressed due to the fact that there were no more scientific questions to answer. To make sure of this, the head of Stephen Hawking checked the mathmatical problem to see if it was actually correct, which it was