Bio-Pod

The Bio-Pod is a Hardmode Pet summoning item that spawns a Bio-Feeder to follow you around. The Bio-Feeder is immune to damage from enemies and despawns upon player death. It has a 1/20 chance of being dropped by Astro Beetles, Lost Probes and Hostile Invaders, which spawn around Meteorites.

Trivia

 * The Bio-Feeder is a reference to the, the fictional extraterrestrial species in the eponymous video game series.