Here’s something a little different for day five of Wales Biodiversity Week. This is not a specific location – it could be at your house, at the bottom of your garden, in the street where you live, in the middle of a city or in the depths of the countryside.

Stone and brick walls are all around us, and they frequently offer superb examples of a biodiverse environment in miniature. The roots of enterprising plants, like ivy and ivy-leaved toadflax, seek out the tiniest cracks and crannies to establish themselves, as do the many varieties of the garden-escapee Campanula species, which are providing magnificent displays in shades of lilac, blue and purple on the walls here in Cardiff right now. On the damper sides of walls and along the bottoms ferns, mosses and lichens make themselves right at home. Bees, birds and ants frequently nest in the larger holes, as do the occasional rats and mice, and a damp crevice at ground level can make the perfect home for a toad.

And then we have the smaller critters – bees and butterflies often bask in the sunshine on walls; slaters, millipedes and snails inhabit the dark spaces between stones and old bricks; and spiders find the gaps convenient places to string their webs. When you’re next out walking, don’t ignore the walls – take a closer look. You might be surprised what you find.