Crystal Ants are enemies that appear on the Dungeon Train in the episode "Dungeon Train." Finn encounters them twice and sees himself fighting them in the future crystal. They pose little threat to Finn the first time around, but when he revisits their car, they attack him. Nevertheless, Finn easily defeats them both times, and his future self makes quick work of them, as well. Despite their low level of difficulty, Finn enjoys fighting them and even makes puns while doing so.
The crystal ants come in at least three different colors: blue, red, and yellow. The blue ants have turquoise gems for eyes, the red ants have yellow ones, and the yellow ants have green ones. Most carry some type of weapon, such as a dagger, club, or sword. Like real ants, they have mandibles. Unlike real ants, they have only four legs. They are about a head shorter than Finn.