Why do my snails get covered in multiple types of algae (Gha, bubble), but my other shelled inverts do not?
Interesting that you brought this up since Liz and I exchanged a quick PM not too long ago in regards to Trochus snail shells. Her tank bred ones had their own microculture of coralline that's a very nice reddish coloration. The wild stuff don't come in with any sort of coralline at all. Over time mine would be covered in coralline.
So the question is what is causing the captive stuff to get covered in algae of any sort, but the wild stuff coming in doesn't have any.
For other shelled inverts, the moltings usually takes care of any sort of algae. I could usually tell when my old cleaner shrimp was due for a molt when the white antenna would start to become covered in some sort of algae. For the ones that don't have an exoskeleton to replace, they usually have some sort of tissue that covers the shell and prevents it.
Conches and Turbos seem to sit still for quite a while at times, and are larger.Specifically my Trochus are covered in algae, but my conchs are spotless. Perhaps the conchs are spotless because they sometimes bury themselves, but even that doesn't make a lot of sense as it's never for long. Turbos also don't seem to get covered in anything except Coralline.