The Phylum Pilocorporea (former Capillosoma) is characterized primarily by the way its organic tissues are organized: cell-like filaments that resemble hair and can assume the most different forms and properties.
A way of putting in perspective, for example, is to imagine that most of the organs, like bones, skin, viscera, nervous system, etc., are composed by different arrangements of the same kind of tissue, like muscular fiber. A super adaptable muscular fiber.
While these “hair-like” tissues are responsible for allowing a high range of anatomical diversification within the phylum, they are extremely dependent on water and humidity, thus the Pilocorporea are almost exclusive of the wet regions of the planet (Equator), and are practically absent on the Polar regions.
The Pilocorporea are also extremely well adapted to withstand high amounts of radiation due to the conditions of living on areas with the most direct solar exposure on the planet.