In my story I have an alien species who was once in the very far past somewhat similar to humans (arms, legs etc.), but that changed drastically in time. They went from a 'normal' body structure to something similar to sentient jelly, i. e. they became sort of liquidous. They also became more and more dependent (and eventually forgot they weren't 'born' into these suits) on mechanical body suits [*] to enable them to interact with the world around them.
I tend to say my aliens are triploid, but I am not sure if that is the right word to describe it. They create their offspring not in male/female-pairs like most species do on Earth, but need the genetic material of three individuals to make one new being. They do not have anything resembling the female/male dimorphism that exists here; every individual is anatomically identical to them without being a hermaphroditic species.
So, does that make sense?
I googled (both in English and German) about ploidy (poli-, di-, tri-, haploidy) and what certain species have it; the way it does not sustain life in humans; and other combinations to get interesting results. I never had the more complex biology in school, so I'm not even sure I understood what I read right.
Thanks in advance.
[*] - The suits are made of nanites and sort of 'grown' with them. Before or very soon after their birth they are injected/coated with a fluid filled with millions of semi-sentient mini-robots which then start to build their armor around their wearers. (edit: 10/10/09 - 09.56h)