There was enough variety for the crabs not to have to fight

The soft crustaceans, which don't grow a fully protective shell of their own, had outgrown their former homes.

But a gift of tropical shells offered ideal new living spaces and "a step up the property ladder", said Peter Jones, a curator at the Sea Life Centre.

There are also enough shells to stop crabs competing for "moving-in" rights.

Mr Jones said the crabs would have first inspected the shells for the amount of space inside and the weight and then slipped out of the old shell and into the new one if they felt comfortable.

He said there was often "fierce competition" for the discarded mollusc casings, but on this occasion there was enough variety of colour and shape to avoid fights breaking out.