Lid on or off with coral?

Stores normally have then exposed and closer to the light so it’s easier for them to sell, while also allowing for you, the buyer, to inspect them fully. Plus the closer you are, the more vibrant you can see their colorations and any possible issues they may have.

Ironically, with saltwater tanks many people prefer not to use a glass lid (but do have a hood to prevent jumpers from being able to jump out) since it traps heat (good for freshwater tanks but not so much saltwater tanks), and any level of salt buildup on the lids would prevent enough light from being able to go in the tank.

If you have a fish or inhabitant that is not known to jump (or long finned/slow), then using a lid or hood isn’t really required. For one that may jump when scared, it’s recommended to at least have a big good to prevent so (while also hiding your lighting equipment).

normally when for sale the lid is off but I think it’s better if it’s on or has a big hood to stop fish from jumping or snails from leaving tank

On, because otherwise some of my critters might escape.