Softgrazer

"Slow, gluttonous, and disturbingly resilient, Softgazers spend most of their lives in deep water, stuffing themselves with carrion, silt, crustaceans, and bottom sludge. Their corrosive stomach acid helps digest all that filth, but over the years it eats away at their insides as well, making older Softgazers look like they’re rotting alive. Outside the body, however, the acid quickly hardens into a gelatinous film used to make basic essence. Their pulsating eardrums help Softgrazers avoid deadlier predators and anglers alike, but they’re also the reason noisy bait works so well on them. The moment one of those rattling contraptions gets too close, a startled Softgrazer lashes out in defense."