We bet your know-it-all friend has never seen this animal
Insane in the membrane
This bizarre organism is a deepwater siphonophore. Siphonophores are cnidarians (hydrozoans to be more precise) closely related to corals, anemones, and jellyfish. The most famous siphonophore is the Portuguese Man o' War, whose deadly sting needs no introduction.
While this mass of floating blue goo appears to be one organism, siphonophores are actually colonies of hundreds of individual polyps. The most amazing part of these animals is that while each individual is the exact same species, they take on drastically different morphology depending on where each individual is located on the colony. In other words, the siphonophore you see in this video is made up of a bunch of individual animals with the same DNA that look and function radically differently in order to form this flotilla of death. Wild!
And no, it's not reef-safe. It's probably not people-safe either.