Alvin

Alvin is the granduncle of Sheldon J. Plankton and only appears in "A Plankton Family Tree."

Description

He is the same shape as his mother, Basia, but sports a pink top hat with a red ribbon

He was born to Seymour and Basia in Bikini Bottom. He has three siblings: the Moe Bros and Ella Plankton.

At some point, according to Plankton, "he disapeared without a trace. All they found was his hat in a pool of ketchup."