What is so fascinating about our deep blue sea is the fact that there could be so many more species than the ones we know about. Our oceans are so vast and deep anything could really be down there. I don't exactly know what you mean by this question but I can give you some deep-sea creatures that have been discovered, although some sound equivalent to science fiction, they are in fact real.
- Giant Isopod: they are a species of aquatic crustacean. Their appearance is that of a much larger bug, similar to those "rolly polly" bugs. They reside in the deep sea scuttling along the seabed and ultimately harmless to humans.
- Vampire Squid: This creature looks similar to many other squids such as their squid-like bodies and tentacles, however, what makes this squid unique is its black webbed skin (resembling a vampire cape) and its red eyes. The vampire squid's body is covered in photophores that produce light to attract prey.
- Frilled Shark: This is an odd-looking shark that lurks in the deep sea. It looks almost pre-historic and can grow up to a length of 7ft with a typical shark fin further down its back as well as the well-known rows of sharp teeth. Its gills appear to be frilled hence its name.
- Anglerfish: These deep-sea creatures are pretty commonly known. They are frightening-looking fish with long thin teeth lining their mouth and the notable luminescent fin ray that it uses to lure other fish to eat.
So these were just some notable deep-sea creatures that I have heard of and I wrote some information about them. Hope this helped :)