Nut Creatures

The Nut Creatures make their appearance in Evicted. They take the form of ordinary nuts, but when crushed they become little colorful creatures. They were seen when Marceline showed them to Finn and Jake. The green one apparently spit some kind of black liquid at Finn, which may have been ink, considering the creature that spat at Finn largely resembles an octopus or squid.

Appearance
The five nut creatures all look very different. The five seen in Evicted are:

Notably, they each have stars somewhere on their bodies.