First time posting here. I know this thread is old, but hopefully tacking this on will help others because this thread is one of the main results that comes up when searching "king snails" online. I'm just copying and pasting a couple of comments I made on Facebook about these snails.
King snails are gorgeous, but unfortunately are hard to keep alive in an aquarium. Or more technically, it could be that they're easy to keep if their needs are met, but nobody houses them properly. Admittedly though, it does seem difficult to provide the kind of habitat that they need.
They're often erroneously assumed to be a rabbit snail, which are snails in the Tylomelania genus within the Pachychilidae family. Rabbit snails are strictly freshwater snails that are restricted to lakes and rivers of the island of Sulawesi. Because king snails are often kept like rabbit snails in the aquarium, they tend to die after just a few days or weeks. Unlike rabbit snails, king snails are in the Cerithidea genus which is not restricted to Sulawesi, and this exact species may not even be found there.
As mentioned, king snails are a species in the Cerithidea genus, and are horn snails of the Potamididae family. As such, they require brackish water, and are more of a sea snail than a freshwater snail. They live in muddy mangrove swamps, and are amphibious. They burrow in the mud at the bottom, but will also crawl several meters out of the water onto rocks and into the mangrove trees. Though they can possibly get by with sand instead of mud, the brackish water and the ability to leave the water are a must to keeping these snails. They may actually be leaving the water to escape the tide, as they seem to feed on in the mud and shallow water, and algae on the roots when the tide is low, and hide in the trees when it comes back in, though they also possibly feed in the trees as well. They keep track of when they need to escape the tide using an internal clock, and so not having a tide in an aquarium could confuse these snails. These snails likely have a brief pelagic larval period that would make them difficult to breed in captivity even if a suitable habitat for adults was provided.
I'm not sure which species of Cerithidea the king snail is, and nobody else seems to be sure either, which is why you rarely see a scientific name associated with them in the hobby. "King snail" is a made-up name in the pet trade, and it's possible the species already has a common name if its identity could be discovered. A related species, the obtuse horn snail or mud creeper (Cerithidea obtusa), is very similar, but is more red and isn't found in the pet trade. I have seen the name "Cerithidea celebes" applied to the king snail in the hobby sometimes, but I'm fairly certain that's a made-up name and isn't a real species. I've never seen that name from a scientific document, and if it were the actual species epithet, it would likely be written as "celebensis", which I've also never seen.
Celebes is an older name for Sulawesi, so it could be that they're a Cerithidea species that's found on Sulawesi though, among other places. This could make them Cerithidea balteata, but I'm not sure what that species looks like aside from the shell. Like many snails, it could also be that there is more than one species with a similar appearance, and so "king snails" could potentially be more than one horn snail in the Cerithidea genus that simply look the same and are confused for each other by those in the hobby.
So I've been doing more digging, and I'm relatively confident that "king snails" are Cerithidea balteata, which is pretty exciting for me, because I've never seen anyone identify them before. Assuming that these snails are truly from Sulawesi, that probably limits them to Cerithidea balteata or Cerithidea dohrni. However, the sculpturing of the shell is like that of C. balteata, but not C, dohrni from what I've seen. C. balteata is also much more widespread on Sulawesi by comparison.
There were a couple of websites/papers that were particularly useful in the ID, which I'll like below. Cerithidea balteata may, with further study, turn out to be several different but similar species, but for now it comprises just one species, and I believe that species is the king snail of the aquarium trade. Of course I could turn out to be completely wrong, but so far I think this is the most reasonable identity of these snails, based on what we know about them. I also want to thank you, Molly Howe, for posting the photo that led me down this rabbit hole. I learned a lot of new stuff about their possible identity.
This page was particularly useful and interesting.
This page was primarily helpful as a means to reasonably rule out C. dohrni as a suspect, particularly the figures of shells.
Cerithidea dohrni Reid, 2014, n. sp. - Plazi TreatmentBank