Oprelian amoeba

From Memory Alpha, the free Star Trek reference

The Oprelian amoeba is a type of unicellular lifeform. They feed on paramecia.

In 2377, Q briefly turned his son into an Oprelian amoeba as a punishment for his inappropriate behavior. He then informed Q Junior that the Q Continuum would see him exist as an amoeba for eternity unless he changed his ways. (VOY: "Q2")