The comparison between phronima and the queen alien morph in the 1979 film Alien seems to originate from Sir David Attenborough's narration in the Blue Planet series. What ever the case the fact remains that phronima is in fact a parasitoid - an animal that predates on its host and eventually kills it. Take the salp for instance, the animal it targets. This barrel shaped animal is attacked by phronima which then bores out its centre and makes a home within which it lives. Phronima attaches itself to its host by using its claws and then propels itself and its new home  through the water. It lays eggs inside the barrel and when these hatch they feed on the rest of the salp, eventually killing it. I found this living phronima specimen on the beach at Derrynane in December managing to observes it behaviour and photographing and filming it.