LongestRoad Neth
From UtterChaos
Neth is a demiplane composed entirely of... Neth. A living being. Entering Neth means floating in liquid- bile and fluids. The walls are fleshy, with hair and teeth and cilia. All around it's pretty gross.
There's a big chamber at one end lined with heads; this is Neth's "brain". The party was flushed to this chamber, where they agreed to trade information (which Neth loves) for portal: more specifically, they would take a Child of Neth (a bit like a silly-putty flesh golem) to the Abyss with them, so that Neth could finally learn about it. Neth is actually pretty nice.