What's the most fascinating sea creature?

Being a horror fan, it’s inevitable that I’ve watched a whole bunch of eco horror about sea creatures. When I watch movies, I often like to look up the movie online after, and I often stray into different sites that deal with the real life subject matter that a film may have used for its concept.
I find that great white sharks are pretty awesome, although they’re nowhere near as deadly as the movies depict them. Most shark attacks are actually accidents, when it mistakes a human for an animal. They also ’‘smell’’ by biting, so there’s that too, that may incite a curious shark to bite a person. I think I remember about certain types of tiger sharks which constantly need to remain active and hyper in order to live. The ones that chew on everything they find lol.
I’ve also learned about the Megalodon, a gigantic prehistoric shark that was so badass it probably played a major role in how sea creatures would act in protecting themselves and forming communities and stuff. So I think sharks are cool.
I also like squids, they look all creepy and cool. There are so many kinds though, I wouldn’t know what information to give about them. I do like the giant and the colossal squid though, those rock.
Angler fish are also quite funky, with all those teeth and that lure on top of their heads, used to attract prey. (a fishing fish, lmao)

So, what’s your favourite sea creature, or, which one fascinates you the most? Why do you think that, and what can you tell us about them? The question has the word sea, but feel free to mention things that live in rivers and lakes, too.