Burrowing conch ID help needed.

[loyalrogue]

This little fella came up out of my sand the other day.
I got a little worried because he completely enveloped the opening of another snail, and I thought he was eating it.
Later on he moved off and the other snail was still in his shell so I'm hoping he's not a snailkiller.
Anyway, here's some closeups, and a larger shot to give some scale, and finally a shot of him burrowing back into the sand.
I thought it might be a fighting conch, but he doesn't exactly match any of the pics I've come across.
Any help in IDing this guy would be appreciated.

 

[Fluff]

Looks like a nassarius snail. Shouldn't be a problem. Great sand stirrer and janitor.

 

[loyalrogue]

Yep. You nailed it.
Thanks!

I was never gonna find that out while I was stuck searching for conchs.

 

[melosu58]

It looks like from the pics that he is doing a great job of stirring the sand.