Those of you who have been able to stab them must have MUCH quicker reflexes than I do. I tried, but could never hit one.
Best luck here was being lucky enough to catch one while he was on a rock that could be pulled out. 2nd best luck was with a trap, you can borrow if you need to, but you'll need a lot of patience. They're really cautious and seem to be able to tell when you're anywhere near.
I have one in my tank now that HAS to have been in there for a long time because I haven't added anything to my big tank in at least a year. He'll come out a little when I scrape coralline if there are big flakes coming down. I seem to notice less nassarius snails than I used to have, but can't be sure it's him. Other than that, I haven't encountered any problems.
But he's still small ..................
The trap I have is an acrylic tube with a weighted sliding door you control with clear fishing line. Casandra's "fancy trap" sounds better, but you're also welcome to try this one.
Good Luck!
Cathy