Not certain about fish, but I think that's a similar case?

Did you know humans are more closely related to catfish than catfish are to dogfish?

QI | No such thing as a fish

¦"yeah, it makes sense why that shape would be favored in water,"

Yeah, I can see that. But also it's swimming in water. Then again if tou want to crawl around the bottom? Hexapod is probably the way to go. But then you also need to be able ro manipulate shit, so frontlimbs become bigger.

Like a lot of space vehicles meant for surface exploring, both imagined and real, are usually six-wheeled, probably for added stability in a rocky terrain where there's a bit less gravity and sometimes storms and whanot. And what is it like on the ocean floor? Rocky, basically "less gravity" and odd flows like storms.

Idk there's a bit more to it I guess, I'm just looking for what that bit is, or if there indeed is one.