It might be an in-law suite, but I can't say for sure.

I don't have a clue what it is but it doesn't have flashing which anything on a roof should. Speaking of roof,something isn't right about the way shingles are installed. I'd have a roofer check roof before closing.

I agree with klem1, those have the appearance of a single or a two tab roof shingle. How old is that roof? The roof to the left of this "stucture" looks odd. I would definitely have a reputable roofer in before I wnet to any contract on this house. In addition to figuring out what the "structure" was for, what is inside it and what is buried above the ceiling.

Raccoon motel? Something funky is going on with the ripple in the roof to the left of this structure. Check it out for sure.

Haha my first thought was I’d paint it bright red like Snoopy’s doghouse and take naps up there 😂 definitely going to have a roofer take a look

It's a solar device to heat water or air. You'll see some of the hardware with it in the attic.

I agree about the roofing. Definitely have that checked and then do some negotiating. I would want that thing, removed, whatever it is. It is a bit on the ugly side.

Seems I certainly could have, however I’m not a contractor, roofer or a 1970’s solar water heater salesman and I certainly wouldn’t have noticed a few pipes from an old solar water heater and said, ”aha, it’s an old solar water heater!” So yeah, posting here to have the strange object identified would probably still have happened.

If you do further investigation let us know what it turns out to be.

Why'd you delete your comment Stax? Your slack-jawed wisdom is the only thing keeping me going through this trying time of solar heater uncertainty :(

Oh and these delicious and affordable generic Pringles. They're outrageous.

Large bird house??