That’s really a good question.
My thinking on golds is that their mantle is either all, or mostly gold.
Here we have a gold ring with what appears to be a purple Centre.
When you first posted, I thought both your clams were croceas... but then started wondering. The top one was actually labelled a derasa but I was stuck between a crocea and a maxima. I went ahead and bought it to check it out... figure the pattern was pretty interesting. Thanks everyone.
Looks more like a maxima than a crocea because of the sides. You can try putting it on a rock and see if it burrows in and then it’s a crocea. Nice either way!
Clam is doing great and definitely more Maxima - elongated shell unlike a Crocea. It is a weird Maxima in that it has a bunch of raised bumps on its mantle which is pretty interesting.