An animated Humuhumunukunukuapua'a
The humuhumunukunukuapua'a, or reef triggerfish, was a type of fish from the coral reefs of Earth. An animated reef triggerfish served as the interface for the children's classroom computers aboard the USS Enterprise-D. (TNG: "Rascals", "Masks")
"Humuhumunukunukuapua'a" is the Hawaiian name for either of two triggerfish species: the Picasso triggerfish (Rhinecanthus aculineatus), and the reef triggerfish (R. rectangulus) The Star Trek Encyclopedia specifies the rectangulus, while the Star Trek Customizable Card Game card's descriptive text indicates the aculineatus. The name means "fish which carries a needle, has a snout, and grunts like a pig".
The computer voice in "Rascals" was provided by an unknown actor.