bubble gum rock was a name that was made up. it looks like that naturally. came in completely covered in coraline and never needed to be cured. mostly all were the same size and shape
I got it at Cap. Bay. I found one reference to it on Google (amongst hundreds of references to music) calling it popcorn rock. It makes a nice addition to an aquascape. Here is a site with an image, although what I got was completely covered with pink coraline: