Is a Pistol Shrimp a bad thing?

[AZDesertRat]

I have heard a popping noise for quite a while and finally got a good look at a pistol shrimp living behind my rock. Are they bad or just a nuisance? I have a Tomato Clown, Coral Beauty, Humbug Damsel and Coral Banded Shrimp for inhabitants along with Mushrooms, Button and Star Polyps and Cabbage Leather. I havent lost anything in close to a year ( a Firefish Goby) but will he bother anything in my reef?

 

[Oze Reefer]

they do little harm.....except dig up your DSB and make that dam noise

 

[Fish_and_XR]

i had a few.. then they mysteriously disappeared when i introduced my mantises....