The planet D'Hoonib is located in the Sidayom system on the other side of the known galaxy. By late-season 1, the turtles are teleported from Earth ending up on D'Hoonnib. It is regarded as a kind of provincial nest, which serves as a playground for all sorts of shady figures. The only known settlement on the planet is the city Peblak; otherwise, the surface is largely covered by forest. The planet also serves as a military garrison of the Federation, which is led by General Blanque, and also the old home and laboratory of Professor Honeycutt is located on it.
Historically the planet gained temporary residents when the Ninja Turtles by an accident with an UtromTransmat were accidentally teleporterd onto the planet and in direct connection the Federation and the Triceratons who where on the hunt for Professor Honeycutt had a fierce military clash on this planet, which ended in a firefight and the retreat of the Triceratons with Honeycutt to their homeworld.
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Some TMNT stuff really isn't for little kids.
In the IDW Comics, the name D'Hoonib appears in the context of a galactic empire in Dimension X which the Utroms had conquered and incorporated into their own territory.