That's extraordinarily cool, but I'm going to need you to take it out of the tank and photograph it in a shallow dish of water to have a good chance at ID'ing it. I would take a stab at it anyway, except that every pic makes it look like something different. Some of the pics DO make it look like a Conus species, but I know what the animals of most of them look like, and don't know of any with that color pattern. The yellow or orange spots are typical of some mitrids, mostly genus Nebularia. But, the shell looks like a miter from a different genus (Strigatella). It might actually be a juvenile volute, although that would be an exceptionally rare hitchhiker. It's going to likely be a worm eater at its present size, whichever it is (assuming it's not a cone snail, and I'm fairly certain it's not). It's a juvenile, and that always makes identification a little more difficult. See if you can get some clear pics of the dorsum and ventrum in a dish of water?
Cheers,
Don