Mysterious Crab

[Hugo Garcia]

I’ve had my tank set up for over a year, and never had added any crabs. My tank is a mostly fish only tank, with 2 anemones and some GSP. So I was caught by surprise one night when I spotted a mysterious crab on the rocks. My theory is that maybe when I was adding pods to the tank, there might some eggs or tiny crab in the bottle. So my concern is if this is a bad crab or a harmless crab. Is have some pictures, and hopefully someone is able to identify it.

 

[laverda]

Harmless IMO

 

[WVNed]

In that kind of tank I wouldn't worry about it. It looks almost like a sally lightfoot crab.
All crabs start tiny but the ones that get big do so pretty fast. The size of your hand in a year.

I have some in my tank and their full grown size is about 1.5 inches. I leave them alone.

 

[Robatusan]

What is his or her objective?