Crab but what kind?

Hi I have found a slow moving crab that seems to be living in a hole in my live rock. It has been tryin for the last 3 days to block the enterance to the cave with bits of rock. When its not busy with blocking the enterance it sits where its tryin to block not really doing much!. I think it has red dot eyes and it has very big/ powerfull claws, its also a kinda dark gray colour. I couldnt really get a good picture as it has never that i have seen come outside the whole. Any ideas ??
K

 

I don't know if anyone else knows what it is but to me that's pretty vague. Sure you can't get a picture or snag it with something?

 

???

Hi sorry i have tried to get a picture but its just a blurrrrrrrrrrrrr! Im just a bit worried as someone told me big claws and red eyes are bad!. do you no any possible names so i could google some and see if i can id it myself?
Thanks K

 

The big bad wolf

Just kidding

Bump...maybe someone else knows.

 

What else is in your tank? Coral or fish?

 

At the mo two clown fish , 1 yellow tailed damsel some snails , a sifting star & 1 cleaner shrimp, a freebie button thing! oh and some micro alge. (IM very new at this!) about 5 crabs that move very quickly that are grey with stripy legs and seem to graze on the live rock, a shrimp that i couldnt id so i took it out if your interested i have a picture of it? ( I took it out as i kept hearing loud clicking which i can still hear now its gone) and the crab that im trying ti figure out if its nasty as its not like the others that scurry around the live rock!
K

 

It could possibly be a mantis shrimp (they are associated with clicking) but they aren't anything like your desciption. Here goes. Does it look like this maybe a different color? I doubt it though.

 

Actually i really really doubt it since they are fast. Anyways I hope someone else chimes in soon.

 

nope! it just looks like a dark colour with big meaty claws and little dot red eyes and he is just alot different from the others as he is slow moving and almost looks like hes guarding his little cave! i just wish my camara would pic him up! anyway here is the shrimp i got out can you id it?

 

Im of to bed gone 11.30 here !
Thanks for your time and if anyone has any ideas post them and ill read them in the morning
K