Abstract bee nest

I spent some time with my grandson Caspar today. He’s very keen on all things mechanical and we spent some time at the park where some work was going on taking down some trees as a result of ash dieback. The workmen showed us an old bees nest which they found in one of the trees and that is my abstract photo for today. Apparently a variety of bees build nests in trees, both living and dead trees, these include bumble bees, carpenter bees and honey bees.