During my recent trip to Andamans (India), I have seen this phenomenon.

A small crab (baby crab) comes out of the hole and makes this round shape out of the sand, and throws in on side making this (perfect) designs. It is surprising that the sand is made perfect round, with uniform size and in placed in right place.

My question is why does the crab make this?

I have attached some photographs with this.

regards,

gandhi

Mumbai, India

nmghi@rediffmail.com

With the exception of sperm whales' off-centre blow-holes and some crabs' single large claw, all complex organisms I can think of are effectively symmetrical along one plane of their body. What is the least symmetrical organism?

Max Maguire, By email, no address supplied