Squid is a mollusk, but it has a feature that most animals can't match, that is vision. We humans and other animals see things through the lens in the eyeball, but our lens has a shortcoming, that is, it can't focus on one point, so most of the things we see are blurred images, but squid is different from us. It has a special crystal in its eyes, which can automatically correct this blurred image, so most of the things it sees are very clear, so we think that most of the things the squid sees are better than us.
It is precisely because the world in its eyes is different from that in our eyes that we call it a four-dimensional creature. Squid is a unique creature. Its lens is different from ours. It can see a very clear image, but we can't, so what it sees is different from ours. So many scientists think that what we humans and other creatures see is three-dimensional, while what squid sees is four-dimensional. Many things seen in squid's eyes are novel, while most things in our human eyes are ordinary.
Squid is called a four-dimensional creature because its eyes are very strange, and its lens has unique functions that we humans and other creatures do not have. They can see many novel things, but our human eyes can't, so scientists call squid four-dimensional creatures, not because squid is superior to us.