Swallowed

Continuing yesterday's arboreal theme, we did a brief tour of the trees in the square on our way out to the market. Three or four more of them have single white spots, so more surgery indicated.

Whilst we were perusing, I noticed this ancient bike lock (I think that's what it was!) which had been swallowed by one of the trees. Since it's now at head height, I wonder if it started lower down and has grown up with the tree? And why has neither of us ever noticed it before???