G.E.L.

" A race of squishy, Non-Newtonian liquid based lifeforms. It’s common for G.E.L. to take on feminine humanoid appearances, which earned the race the nickname, “Slime Girls”, though they actually have the ability to change various parts of their bodies by shifting their internal fluid around, and are therefore fully capable of taking on masculine humanoid appearances as well as other shapes."

~ "A Layman's Guide to the Stars", Ch 49: Just Add Water

G.E.L. can reproduce asexually, or with partners of any gender and any species. In doing so, the child is guaranteed to be born a G.E.L. though their shape may take on features of the donor species of the genetic sample.