Gonna blame  afterhumanity333 for this one. We were talking about shark characters and the idea of a "sharkadillo" came up, so yeah! This version is half shark, half armadillo. And to be frank, he couldn't be happier!
After trying to escape a self-detonating illegal gene lab, Toughset decided to go after the villian instead of defuse the bomb. He didn't get out in time, but was far enough away from a lethal radius. After a month or so of recovery, his genes were altered, not destroyed. And being so close to the ocean, well, you can guess where the shark influence came from!
Thing is, he spent so many grueling years having the inablility of being anything more than a floatie in water, so the sudden ability to submerge, and be quite agile underwater as well, was utterly liberating to him! You can catch him in California and mexico on the beaches, acting as a lifeguard, and testing out Muay Thai kickboxing on the side.