smashers are typically much much smaller than the ones seen on the videos/youtube. You probably have one of the ones from the atlantic. I had a shipment of LR once that had 5 or 6 of them in there...because my tank wasn't set up - it was just about finding the LR, and squirting some RO water in their hole. They pop out very fast though like centipedes. I gave mine away to a local reef club (this was before I moved to NJ).
bottle trap is probably the best way to go. You could put a small emerald crab in there as bait...lol - j/k. you must have been hearing a lot of "clicking" sounds from the tank all this time.
I did hear it for months. Just assumed it was a pistol...I was wrong lol