need advice

[rmleal]

hi i just relized i have a mantis shrimp in my tank a baby a small one but what i did was take the rock out of my tank and flushed it with freash water. but i didnt get him ou. i had to break the rock open to get him out he was dead but i have to ruine my rock. my question is can i get rock without these critters or is there a special way to flush the rock so i dont get these bad things

 

[farslayer]

One of the best ways is to just get a mantis shrimp trap and bait him out. You could also locate the rock he is in and then put it in a bucket of saltwater. Turn out the lights and put some shrimp in there for him to eat. When he leaves the safety of his rock for the shrimp, grab the rock and put it back in your tank.
You can always isolate your LR before you introduce it into your tank, but that is one of the risks, you don't always know what you're getting. Mantis shrimps make popping noises and drill holes in the rocks, so those can be used as indicators of their presense.