Is this a Nassarius snail or Whelk?

[Gojjie24]

I have a bare bottom tank with a lot of SPS corals and a couple LPS. Have a couple of these guys that come out only at night. Thinking it is a whelk, but figured I’d get a couple other opinions. I’m also curious if this type of snail is bad for the tank.

 

[kevgib67]

I have a bare bottom tank with a lot of SPS corals and a couple LPS. Have a couple of these guys that come out only at night. Thinking it is a whelk, but figured I’d get a couple other opinions. I’m also curious if this type of snail is bad for the tank.

Looks like a whelk to me, siphon appears mottled. Unlike nassarius snails they don’t go under the sand ( I realize your bare bottom) and are nocturnal. Here’s one I pulled from my tank a few years ago.

 

[papercrab]

Some welks are active hunters an most sea shells you will find at the beach will have small holes in the top where a dog welk has drilled a hole and injected stuff to melt the insides of the snail.