EVERYTHING, LOL, color wise is common for clams. I have an emerald green squamosa with shiney turqouise spots. I also had a squamosa/crocea hybrid. I have seen some pretty weird colored clams before. Those are all sort of basic. Just some may be from deeper down and will, most likely, change color at some point. Clams try to cut off eachothers mantles and incurrent syphons as well. This causes darker or lighter coloration too. Watch out for that junk. There are like 7 clams in that tank, make sure that they don't start fighting for right over a certain flow area.
The only thing I might do is add some SPS frags to grow them out. With that amount of technology on the tank, they should grow out pretty quickly.