As exciting as this would be, I HIGHLY DOUBT that your clams actually bred. When clams breed, they spew millions of eggs into the water column. It takes a very long time for these eggs to settle out, go through their metamorphic stage and actually become a "clam." Also, the "baby clams" have no xooanthella, so have no color at all. The only way, when bred in a tank, for the babies to obtain xooanthella, is to kill a live clam, put it in a blender, blend it up, and dump it in the water. Then, the baby clams get their xooanthella, from the blended clam.