Marceline's phone appears as a small crawling bug-like octopus at first. When Marceline grasps it in her hand, it takes on a fish-like appearance and grows to the size of an average house phone. It is blue in both its condensed and full-sized forms.
When Marceline's phone is in its condensed form, it closely resembles the green octopus Nut Creature.
When enlarged, the phone resembles a lamprey, an eel-like vertebrate known for its jawless mouth and blood-sucking ability.