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A being with a lot in common with Tethys the sea-troll.

Chatogaster is first encountered as an oxygen-rich liquid lifeform masquerading as a lake on the planet Band. Being water-based, his/her essence and sentience are distributed throughout every drop. Band is the nursery planet for young Sun-dogs. So every time a sun-dog comes to Chatogaster to drink, it incorporates a little of that sentience and, even in deep space, maintains a telepathic link with the water-being.

Chatogaster strikes up a deal with Dom Sabalos, who agrees to take a little of the water back to Widdershins with him so that Chatogaster may live there in the great ocean of Tethys.