- "The Isle of the Deep is really not a single creature but a colony of thousands of individual tubules, an aquatic vector of the Mind Worm which terrorizes Planet's continents. Over its lifetime, certain tubules secrete a tough gluelike substance which hardens to form the characteristic shell that floats the colony and creates the appearance of a rogue island."
- ―Lady Deirdre Skye
"A Comparative Biology of Planet" The Isle of the Deep is an aquatic breed of the Mind Worm, Planet's dominant animal species, which patrols the seas of Planet. It is made up of thousands of tubules that all work as a collective for every purpose.
An Isle of the Deep forms when an aquatic Mind Worm Boil is born in a mass of Sea Fungus. The worms bind themselves together at birth by means of a strong adhesive they secrete, which also hardens to form the buoyant shell that floats the Isle. An Isle of the Deep tubule has a similar build to its terrestrial cousin, with the same leech-like jaws and long antennae, but with smooth blue skin. The colony moves about by sailing whilst rotating in the general direction of its destination. It floats by use of its buoyant shell and by gas pockets within the Isle.
The Isle of the Deep utilizes the same psionic attack methods used by the Mind Worms, stunning the crews of terran ships before running them through. Periodically, Mind Worm Boils will break off from the Isle, which are carried to the shores by the Isle, leaving them to make cross-continental raids against human colonies.
Like Mind Worms, the Isles yield Planetpearls in husks they leave after being cooked by a Flame Gun. Isles of the Deep can be bred to be used as naval units and sea transports. How much they can carry depends on the size of the boil.