What is this?

Any idea what this is?
I saw this on one of my walks in the area round Marsden. I have no idea what it was, and it is difficult to be sure of its size. If I had to guess, I'd say it was about four feet across and on a pole, going down into an unseen dip, about six to ten feet high.

When I did the Kintyre Way with Ani Sherab and Phen it was extremely enjoyable, but it was not what I had originally planned to do. My original idea had been to do the walk solo, and use it in part to assess my current level of walking, navigation, and other skills needed for hill walking. So I decided to go off to the Peak District for a couple of days, to do these odds and ends.

Some of the lessons I have learned, from both this couple of days, and the Kintyre Way.
I'm not as young as I used to be.
I'm not as fit as I used to be.
I'm not as fast as I used to be.
My navigation skills need a little bit of refreshing - I managed to make one minor mistake in my navigation, which was perfectly OK in the situation, but in different circumstances could have been significant.
Going up hill is hard work - doubly so in direct sunshine all day, on the hottest day of my year so far.
My own stamina and speed is the limiting factor on my walking - as it is for boating. A walk of 21.5km and 770m climbing was beyond me since it would have taken me more than 8 1/2 hours - and I wasn't prepared to do that, so terminated it at a point where I had some choices as to where I went. By contrast on the following day a walk of 15.5km and 425m rise was a doddle.
I should do only one thing at a time. If I am primarily walking, take the minimum photographic gear possible, and store the camera away except when I stop deliberately to take photos; contrariwise, if I am primarily taking photos, then I should walk the minimum necessary to get to where I am taking photos; should have my gear packed away until I am on site; and should have the minimum amount of gear necessary for whatever photo opportunity I am exploiting.

There are some hugely attractive locations in this country, and it is a long time since I walked to enjoy them.
Marsden garden