Skate - ugh - caught one years back on a seaworm at Plum Island. It was perhaps 14 or 16" across, a few pounds, had absolutely no fight, but was like hauling in a rock.
Then I got to unhook it. They have a bottom slung mouth which is like rubber and which the hook seemed glued into. Not to mention trying to stay away from the tail jobbies which I do not believe are poisonous, but which I didn't want to find out the hard way about.
I've talked to people in Fla who have hooked into big sting rays; they are low gear tractors; don't move very fast, but unstoppable even on tarpon tackle.
L.