Fluttershy didn’t even bother with getting a merform: that’s how passionate she is about the subject.
Remember! As a general rule, turtles (the ones with the webbed feet or flippers, for swimming) live in the water, whereas tortoises (with the ploddy, definitely-not-for-water legs) are one of the only things that can’t swim. There’s this song/vid, too!
“You get sea turtles, not sea tortoises.”