Rainchild is a light blue plankton with 6 light teal spikes on his head. Like all other plankton, he is small and he has one eye. His eye color is light yellow with a black pupil. He also has buck teeth.
When Plankton calls his family to help him obtain the Krabby Patty Formula, Rainchild along with many other of Plankton's relatives show up. They then get the fake formula and once seeing that the secret ingredient is plankton, they all run out of the Krusty Krab.
Rainchild appears as a boss in the game Plankton's Robotic Revenge. He is the first boss that appears in Dutchman's Triangle and he is in a robot suit. After defeating him, SpongeBob and the gang get one of the three keys and they continue their adventure to Rock Bottom.