finding crabs in the reef

[spicoly]

i was doing some aquascaping in the tank and found some crabs and cought 1 but still have about 3 more and i was wondering if you could help in telling me if it a good thing or a bad guy this one is brown and zebra like the other one is huge and stuck in a rock

[spicoly]

also found a big full brow like. the size of a twonie very ugly does any one have link to a site where i can ID this guy an what do i do with them put them in the refugium

[atlantic]

generally the bigger the crab the more distructive. if you had pics im sure we could give you a better answer though.