Grave is Xaxon's Ectonurite (a species from the planet Anur Phaetos) form, just as Ghostfreak is Ben's Ectonurite form. He appears as a ghostly apparition with grey skin. He has one purple eye with a black pupil. Rather than legs, he has a grey tail. His arms are long and spindly. While most Ectonurites have small grey hands in covered form, Grave usually has his true form's hands: large purplish-grey hands with yellow spikes jutting from the top and long, large, dark-blue claws in place of fingers. He has large yellow spikes sticking out of his shoulders with some of his true skin exposed. His head is a strange grey dome. He has black lines running all across his body except his hands and shoulders. His Protomnitrix Symbol is on his chest, imbedded in his eyetrack.
As an Ectonurite, Grave can fly, become invisible, possess people, see all around himself by sliding his eyes along a black track on his outer skin, phase through matter, and peel back his outer layer of skin to reveal tentacles; from there, he can either fire a purple energy blast or reveal some unfathomably disturbing image.