You'd be forgiven for thinking this is a shell, although it's actually very delicate and tiny fungus (less than 4mm across) that has appeared in potting compost (the broad beans have so far failed to show.)
Extra: Braving the early frosty air, I donned my thickest cycling jacket, put my compact camera in the pocket of said jacket, and set off for exercise/something to blip. Unfortunately, when I stopped to use it, the tele lens extended out completely with the shutter failing to work. A system error warning appeared and, try as I might, the lens stood proud, refusing to retract. It took me half an hour of fiddling before I could get the tumescent camera back in my pocket. Embarassing.
I took this tractor on my phone. 

Many thanks to Cathy1947 for hosting.