If you’re pressed for time, fast forward to 37 seconds. (Sadly, it meets its demise in the end.)
A comb jelly is a distant relative of the jellyfish. From Smithsonian Ocean:
Jellyfish and comb jellies are gelatinous animals that drift through the ocean’s water column around the world. They are both beautiful—the jellyfish with their pulsating bells and long, trailing tentacles, and the comb jellies with their paddling combs generating rainbow-like colors. Yet though they look similar in some ways, jellyfish and comb jellies are not very close relatives (being in different phyla—Cnidaria and Ctenophora, respectively) and have very different life histories. Both groups are ancient animals, having roamed the seas for at least 500 million years.
The comb rows of most planktonic ctenophores produce a rainbow effect, which is not caused by bioluminescence but by the scattering of light as the combs move. Most species are also bioluminescent, but the light is usually blue or green and can only be seen in darkness.
There are just too many sizes and shapes of living things here on our planet to assume that creatures from another galaxy, or even our galaxy, if they exist, look like us.