A rock under water exposed to the sun.

@odd You're right about the sun, but the materials are off.

@maique I understand. This one might be suitable for you, though. I hope it stands on its own, without the puzzle.

@maique Wall of "some sort" is right. No digital computers except in my camera.

Is it an ice sheet on the water, plus some rocky ice beneath the surface, with the sunlight shining on it?

@maique No. Colder. Non-smoker, for one thing...

@maique /me looks at the photo for a long time.

No. Not smoke, not steam. Light puzzle.

I think it's something underwater in a container.

@vincent No water. No container. But some plastic.

Is it remains of plastic that has covered the darker surface?

@odd And is it rye bread?

something thawing?

@odd Or a painting (now partly covered in plastic).

@vincent Nope, not at all.

@odd Old plastic covering is involved. No bread. No food, no water.

@odd Not a painting, but there is paint. Perhaps it would help if I said the scale is small, no more than 10cm wide, likely less.

A cobweb on something painted?

@odd Not cobwebs.

Light reflecting on a painted wooden fence piece. Reflection is coming from ... well, you've said old plastic covering so I'll say plastic covering a bucket.

I've seen patterns like that on a ship's hull so the reflection could be from water ... on the plastic.

part of a window? The only reason I said underwater, or perhaps window, is that I see artefacts above it.

@acfusco Light reflecting off plastic onto something painted is correct. No bucket, no fence.

@acfusco No water involved here. There are wave-like structures, but you wouldn't call them waves.

@vincent The painted wood is part of a hand-made window frame.

So it’s a window frame in a shed, with a broken plastic window?

@odd Nope. Hand-made window in my house, built by a shop teacher, forty years ago. So, where might the plastic come in?

Did you just put some cling film/gladpack in your window? Else, I give up.

@odd Yes, it is the 3M insulating film from last winter. The tape has failed and the plastic curled up. Pictures tomorrow.

@odd @maique @vincent @acfusco

Here is a zoomed out view of the window, the 3M film collapsing, and the resulting caustic reflections.

Makes more sense now. I’ve never seen such film being used before. Are the windows one pane of glass? (Building code here demands double paned as a minimum I think).

Makes more sense now. I’ve never seen such film being used before. Are the windows one pane of glass? (Building code here demands double paned as a minimum I think).

@odd It’s a big picture window, but built by hand with two by fours and single paned glass. Some of them are stained glass. I have nearly replaced it five or six times, but then I worry about losing the uniqueness. But it leaks, air and water. So the shrink wrap gets me through the winter. But at some point, it will have to go.