In the past I revealed that in my AU Spike's biological father is Gaius, the ancient Dragon Lord. I wrote about how that is possible HERE.

So it's time to draw his biological mother. There's no name, and her design is based on Lauren Faust's sketch of a female dragon (even the shininess).

In this case her being called 'ancient crystal dragon' doesn't mean she lived in the ancient times (unlike for Gaius). I'm gonna go more into it when I make a headcanon post about dragons, but at one point when a dragon reaches a certain age (and size also), they gain the title of 'Ancient Dragon'.
Because of dragons' possible long life span, she may still be alive and be around, but I have no plan of her being part of my AU story (at least currently I don't).