abalones are temperate species usually, you would need to run a chiller or they would die pre-maturely on you. Tropical large snails are things like conchs and larger astreae species, like the Astreae tuber. Queen conchs are too big, they bulldoze around and climb on rocks etc... Fighting conchs like mentioned are a good size, there are a lot of large marine snails. Most in the hobby are beneficial cleaners, but there are a lot more predatory ones that are cool. Google image search "Murex Shells/Snails" "Tulip Snails" " Florida Horse Conch" "Comb Murex" "Gaudy Natica" "Purple Moon Snail", "Crown Conch" etc...