Consider a prized camera, being borrowed by a 3 year-old for some unsupervised roving photography all around the house. (Like his brother, he’s been self-sufficient on computers and cameras since about age 2.5, so this is not unusual here.) Listen for the shutter clicks all around as the brat roams. Relax and get back to work. An hour later, notice the camera, its job now finished, sitting someplace. Note with horror how its lens cap has gone missing.

What would you do?

1) Interrogate offspring for the whereabouts of the little plastic thingie.
2) Look for it yourself.
3) Review the saved photos on the camera.

The winning option was #3 in the case of this morning. During his expedition, Stuart recorded the following picture, showing a black circle lying near some rags. The rags were distinctive enough for me to walk straight there and find the lens cap.