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From Wend's Complete Marine Bestiary, Volume 2 (Aquatic, Warm-Blooded Megafauna):

"'Giant pangolin-otters live in the ocean, usually confining themselves to the area around an island chain. They move between the deeper and shallower waters as they please, propelled by their long, powerful tails. They are also technically amphibious, though they almost never venture onto land and can only manage a sluggish crawl."

"Their diet consists mainly of small fish, for which they have a unique method of hunting: an individual pangolin-otter will approach a large school, and then swing one of his giant claws straight through it. A sizeable number of fish will be either killed or stunned, and they are then casually swept up by the creature’s long, adhesive tongue."

"The pangolin-otter’s back is covered with armor-like scales, which provide it with protection from creatures such as small sharks and barracudas that are also drawn to the schooling fish. Pangolin-otters focus more of defense than offense, and when presented with a creature that can threaten them, they almost always retreat to find safer feeding grounds."

"The hard, solid nature of the creature’s scales makes them ideal spots for barnacles, which pangolin-otters regularly scrape off against rock outcroppings. More tenacious are the whale mites, which sometimes crawl between the scales and thus go unmolested."

"One interesting feature of the pangolin-otter’s tongue is that it can taste the water around it, its large surface area giving it an acute sense of underwater “smell.” This allows the pangolin-otter to locate islands while in open ocean by detecting the water-borne minerals that indicate land. For this reason, sailors lost at sea will follow any giant pangolin-otter that they encounter in hopes that it will lead them to shore.'"

The pangolin-otter, befriended by Yue, who pulls the Gaang Jr.'s ship.