Aquatic Flumph
Despite their name, aquatic flumph are unrelated to the flying creatures of the underdark. They have eyestalks, tentacles, and a mood-based glow like the underdark race, but are more closely related to the jellyfish. They average about six inches wide and twice that in height, from eyestalk to tentacle. They're fully aquatic and propell themselves through water as a jellyfish would. If put on land, they suffocate and die within two minutes.
Their intelligence level is below that of an octopus, but they seem to have some degree to emotional intelligence. They're social creatures and live in clusters in the wild, swimming in tight bunches that were once assumed to be one large creature. They react to each other's moods and will all glow the same color.
Aquatic flumphs are common pets among the triton and other seafaring races. Occasionally, an aquatic flumph will be separated from their cluster, either injured, lost, or rejected. If picked up by a humanoid, they'll often bond with their new family and refuse to leave. In captivity, they have been seen to react to the emotional states of those around them, similar to how they react in clusters.
They can be difficult to maintain, especially by any land-dwelling humanoids, due to how much salt water they need to get adequate exercise and enrichment. They're highly social creatures and love being around many different people.
the flabbergastedness i had when i heard she had one. a happy accident that has given us this lovely little convergent-evolution blorbo