HCA: Hermit Crab Association

Sorry, I've been asking a lot of questions recently.
My question here is if the shells look okay. I noticed on one of the shells that there was red stuff and after boiling them, there was white residue on them. Is this dangerous to the crabs? I received these new ones today and had them shipped from Naples Seashell Company.
https://imgur.com/a/kjjgp2R
The shells mainly consist of apple murexes and green turbos

You should be safe with those shells. Sometimes if you boil the shells for too long they turn white. We have several shells like that. There was another post a week or two ago about wiping shells with organic extra virgin olive oil. We never tried that before. After that post we tried it and it did clean the shell up.I don''t know how long it will last but they did look better. I'm not sure what the red would be from. Maybe a barnacle or something?

edit: Don't be worried about asking questions. That's how you learn! Our care sheets are a great resource too!