In Shantae, they are red snakes with yellow eyes and three teeth. In Pirate's Curse their looks are similar, but they add a new variant: the slug. Slugs only appear in the sewers. They are green, and they only have an eye and a tooth. In the artwork of Half-Genie Hero, they mix the two creatures, beeing red snakes with an eye and a tooth.
They drop out of holes in groups of four. constantly respawning. They move back and forth. In Pirate's Curse, snakes have 1 HP and slugs have 2 HP
Because of its peculiar way of spawning, fans compare it to the Shemum from Kid Ikarus.