Clams are a novelty at best in the aquarium. An hour after you put them in the tank the'll be gone and youll be lucky if you see them poking out of the substrate every once in a while.
If you have live plants in your tank they could uproot some of those that dont have good root foundations. Ive had mine for a little over a year and have seen him maybe 10 times and some of those were when I was replanting and would find him. Then id pull him out and move him. an hour later he will be gone again heh.