Seaweed

Can be uncommonly found in Jungle's Ivy Chests.

Usage
Used via left clicking the item on your hotbar, it spawns a turtle approx. 1 block high and 2 block wide that, unlike pet bunnies, flies around using rotors on its shell.

Trivia
It's a possible reference to Rainbow Dash's pet tortoise Tank from the animated series My Little Pony: Friendship is Magic, which also uses helicopter-like rotors on its shell to fly. Like most pets it does not do any damage to enemies.