Amber Mosquito

The Amber Mosquito is a pet-summoning item that spawns a Baby Dinosaur to follow the player around. If it is too far away from the player, a pterosaur will carry it by the tail to continue following the player. Like other pets, the Baby Dinosaur is immune to damage (including from enemies) and despawns upon player death, unless in the pet slot. This item can only be obtained by putting Silt, Slush, or into an Extractinator. With Silt or Slush, it has a 0 chance to drop, with the rarer Desert Fossils a slightly higher chance of 0.

Trivia

 * This item is a reference to the American science fiction media franchise , where dinosaurs are cloned using blood found in mosquitoes trapped in amber.
 * Despite it's extreme rarity, the Amber Mosquito can be obtained pretty easily due to the rather high abundance of Desert Fossils in the Underground Desert.