is this a nassarius snail? i have 2 of these monsters and they are really bigger than any other nassarius i have. they are about an inch in length and really dwarf the other ones.
definitely looks like one, but an inch is rather large. there is a predatory whelk, i believe it is, that gets larger than a nassy and is well, predatory. i read a post recently by waterfaller, i think, about them. try searching
That IS a nassarius snail. There are 2 sizes common in the hobby. I have about 15 nassarius snails that are about 1" long. They were sold to me as Hawaiian Nassarius. I am certain that is what you have. Sorry I don't have a scientific name for you. Mine are wonderful scavengers, sometimes too effective as they will pull food away from my corals, especially the ones on the sand bed.
In the pic... Nassarius on left and Whelk on right.
Notice the pattern on the whelk's snorkle.
Also, the whelk has a protective shell on its tail that it uses to seal itself in its shell when in danger (more like regular snails in that regard). I don't think nassarius snails have this with their big foot they use to almost fly across the sand.
In all pics I have seen of whelks they have darker shells with white patches compared to lighter shells of nassarius snails.
Hope this helps.