HCA: Hermit Crab Association

Are these safe to use? I can't find info on whether or not the sea life is all natural or if any chemicals were used on them. I have contacted the seller (for the star fish) that hobby lobby uses and have not heard back yet.

I want to use the shell bits in the water bowls.

The sea life has been chemically whitened somehow. Natural sand dollars are dark grey and starfish are grungy looking as well.

The shell chips should be okay so long as they have no polishing agents, or a coating.

Any recommendations on where to get those items? I want to make sure they are collected with respect to the ocean and its health. At the same time, I want to meet as many needs of my hermies as I can.

How do I tell if it has a coating? It's iridescent/pearly but I'm not sure if that's natural or not. I know some shell insides are like that though so it could be natural.