Filter feeders of one type or another. Only one to be concerned about is the first, which is a vermetid snail. They throw a net out to capture food. This net, from the large ones, can irritate and kill coral.
Well, so far I do not have coral in my tank but are they harmful to my fish and how do I get rid of them? I need to get a better zoom so I can see them better. Thank you for your help in identifying them, I couldn't find anything online to identify them myself, so thank you 😃