One of the best ways to clean shells and corals is with a bleach solution. Usually 1 cup chlorine bleach to a gallon of water. Just let the shells soak in the mild bleach solution for a couple of hours. Take a brush and scrub the outside to remove any unwanted growth. Don't use too strong a solution or soak too long, the bleach will dissolve the shell.
That said....My opinion is the same as others, please make sure the shells you pick up aren't homes for creatures. I collect shells too and this is the method I use to clean them. I also have pieces of dead coral bought years ago, before my diving life started, for my salt water aquarium. This same bleach solution will clean the algae from even the delicate pieces.
That said....My opinion is the same as others, please make sure the shells you pick up aren't homes for creatures. I collect shells too and this is the method I use to clean them. I also have pieces of dead coral bought years ago, before my diving life started, for my salt water aquarium. This same bleach solution will clean the algae from even the delicate pieces.