No stranger to capturing unique and wonderful scuba diving experiences in Melbourne, Australia, PADI scuba diver PT Hirschfield has recently come across a pyramid consisting of hundreds of spider crabs.

In 2014, PT witnessed thousands of spider crabs migrating in Port Philip Bay and this recent encounter again highlights the interesting behaviour of these marine critters.

There are numerous theories about the spider crab migration, however the most common thought is that the crabs converge in this particular area to moult their exoskeleton and mate.

You can view more of PT’s diving adventures at