Brain Corals are seen in the episode Patrick SmartPants, when Patrick and SpongeBob are running in Jellyfish Fields and Patrick runs straight through a warning sign and falls off the edge of a cliff, landing in a field of Brain Coral. If one plugs a brain coral into his body, this person will become extremely intelligent.
The brain coral is located in the Jellyfish Fields.
The Brain Coral is the same color as Patrick's head. It has a plug in it, as if it were an electronic device.