ent(o)-

Within; inside.

Greek entos, within.

A visual image that is entoptic occurs or originates inside the eye; an entamoeba is an amoeba that typically lives harmlessly in the gut; the Entoprocta is a small phylum of sedentary aquatic invertebrates (Greek prōktos, anus, the anus being within a ring of tentacles). Other examples are relatively rare or are variant forms of those in endo‑.