Caterpillars and cocoons, sea serpents, a seahorse and a mermaid

On the south face of the western arch, on the right side as you look at it, is a pair of sculptures that is recognisable, referring to metamorphosis: that change from one form into another, like a maggot into a fly, a caterpillar into a butterfly, from an egg via a cocoon. A pair of five-petalled flowers, not a butterfly, is juxtaposed.