The Medusoid (Na’vi: Rimo’a) is a primitive airborne life-form that is typically found drifting above Pandora’s oceans, rivers or lakes. Much like a Terran man-o’-war jellyfish, the Medusoid possesses long, stinging tentacles that can be used to stun and capture prey for feeding. Their body is composed of a large bladder that is full of hydrogen gas, which is produced as they digest their prey in an organ similar to a bovine rumen. This gas production, and a set of waste-water bladders, allows them to regulate their altitude and float far above Pandora’s surface. Through the use of steering vanes and minimally-propulsive aft fins the Medusoid can subtly angle itself toward potential food sources, but is otherwise passively carried by wind currents.

Very little flesh on the Medusoid is edible, leading most predators to avoid these creatures lest they risk the explosive release of the stored hydrogen gas or an encounter with its tentacles. The rubbery appendages are covered in sensors which are capable of responding to the touch of an animal with a speed that is belied by the Medusoid’s slow grace. Once ensnared, electrocysts in the tentacles produce a shock which is powerful enough to ward off large predators or even kill a full-grown human. Only the Great Leonopteryx is known to hunt these creatures if desperate for food.

The Tlalim Clan has learned how to harness these massive creatures for aerial transport, gently coaxing and steering them through the air with the help of specially constructed airship platforms and a secondary creature, the Windray. Though slow-moving, the Medusoid is capable of carrying tens of thousands of pounds over long distances- a valuable feat to a nomadic clan.