Chtorran Gastropede

Chtorran Gastropedes (commonly known as "Worms") are the main antagonists of the The War Against the Chtorr series.

Biology
They range in size from as small as a dog to as large as a bus, or even larger. They're normally bright red, but have been seen in other colors ranging from white to green. They have two "arms" with claws, and are very dexterous. Their bodies are covered with symbiotic "fur", each strand of which is a distinct lifeform and acts as a sensory input.

Worms are capable of remarkable acts of problem solving and interaction and some have been observed to understand a rudimentary form of English, but both their intelligence and their communication abilities have yet to be fully understood. As long as they eat meat, they can continue to grow. Their growth slows down when they feed only on vegetation, but their appetite gets much larger.

Culture and society
It is understood that a worm "family" consists of four individuals, though their roles are unclear. When a group of worms form a family, they build a large, domed structure referred to as a hut. The worms live in a series of tunnels within and beneath the huts. When many huts are built close together, they start to merge into larger huts, and so on. This process repeats recursively, forming Chtorran cities which the military calls mandalas due to their spiraling shapes. When a worm reaches a mass that makes it unable to move, it will crawl into a dead end corner and eventually die.