I'm sorry to tell you that I had to hunt him down and find the rock he was hiding in. Then I took the rock out and noticed the hole that he hid in went straight through the rock, so I took a bamboo skewer and pushed him out the other side into a critter keeper.
I later put the critter keeper into the tank so he'd live and gave him to another reefer. (mantis are pretty neat to watch)
For the other, I actually broke the rock open and found a tunnel system with a trap door hiding spot masked to look like the rock!! They are very smart!!
I have heard of lots of people trying the exterminator trap (brand name) with no success. I would have tried, but I paid for it and it never came in the mail.
Some others have tried a pop bottle and cut the top off. Then they take the part they took off and stuck it back in the bottom half inverted so when the mantis swims to catch any bait, the can't find their way out. (Honestly, I think they are smart enough to find out after a while) I have heard more success with this method than with any other of the "trap" methods.
Good luck and....
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