Symbiote
For the Trill companion species, please see Trill symbiont.
A symbiote was an organism that lived in symbiosis with another.
After a multidimensional fungal parasite attached itself to the arm of Sylvia Tilly in 2257, cutting it off was rejected as an option, because if the creature turned out to be a symbiote, the action might kill her. (DIS: "An Obol for Charon")