- Any of various primitive organisms, a naked mass or protoplasm in diverse taxonomic classifications:
- protists of the Amoebozoa
- protists of the order Acrasida
- Parasitic rhizarian chromists of the order Plasmodiophorida
- The slime nets, of the class Labyrinthulea of chromists
- Cellular slime molds of the genus Fonticula, in a sister group of the Fungi.