Plankton tries hard to get Mister Mussel to return a friendly greeting, but when Mussel finally opens his mouth the results are unfortunate for Plankton.
When Crabby gets sick, Plankton is determined to play doctor and take care of his friend, even if Crabby does not want the help--until Crabby realizes that he can get Plankton to do all of his household chores.