Well, they're called asari. They look mostly human, except for the blue skin and instead of hair they have, erm... [Shepard sort of reaches up and touches the top of her head as she grasps for some way to describe it.] I think it's something like cartilage? Some people think it looks like tentacles, but that's not what it is.

Anyway, they're extremely long-lived, and they don't reproduce sexually, from what I understand. I'm no xenobiologist, though.