Larger and more massive than any Human-era land animal at 16.375 feet (5 meters) high and 8.8125 tons (8 tonnes) in weight, a Megasquid can be seen pushing its way through the soaking vegetation, splintering conifer trunks and pulping the branches of lichen trees as it goes. Air passing through its body causes internal membranes (the megasquid's equivalent of vocal cords) to vibrate and amplify any sound it produced. The sound is amplified by means of a balloon-like sac on the terasquid's forehead which expands and vibrates like with the vocal sac of a frog. As it moves through the forest, the megasquid stakes its territory by bellowing out signals through the drumming rain.Eight legs, each as broad as a tree trunk, support the beast as it lumbers through the forest, moving at speeds similar to a human's walking pace. When the animal is at rest, its legs are compressed and solid. An interlacing network of cartilage within each column locks together, forming a rigid support for the enormous weight of the animal. In motion, the limbs are lengthened, raising the Megasquid from the ground and allowing alternate pairs of legs to swing forward. Walking on eight legs is not easy, but the megasquid achieves it with a slow, fluid gait, in which two pairs on opposing sides of the body alternate turns with each stride. It can move at about 2,362 feet (720 meters) per hour.
A pair of large flexible tentacles reaches out in front of the megasquid, extending to 13.0625 feet (4 meters) in length. With their dexterous tips, these tentacles gather fruit (especially lichen fruit), young leaves and shoots, as well as tree-dwelling creatures (especially young squibbons) and their nests. Food is then delivered to the terasquid's mouth, at the center of its ring of legs. Despite its massive size, the Megasquid's food requirements are relatively small for its bulk. Being ectothermic, it does not need to burn food to maintain its body temperature, and can stay constantly active due to gigantothermy. It therefore needs only about one-tenth of the amount of food that a similar-sized warm-blooded creature would require, or not more than 66 pounds (30 kilograms) a day. Consequently, the Northern Forest can support large populations of megasquid.
Unlike its ancestors, the Megasquid is not clever. However, it does not have to be. With plenty of food so readily available, the absence of predators to the adults, and movement achieved by the simplest of processes, the brain of a Megasquid is tiny. It weighs only 14.03125 ounces (400 grams), or 1/20,000th of its owner's overall mass. Nevertheless, the Megasquid are social creatures and constantly communicate with one another across the Northern Forest.
Sometimes, a Megasquid can be bodily hijacked by a slithersucker (deceiving the animal by pretending to be a lichen fruit) in order for the slime mold to get dispersed.