Sitting in garden about lunchtime. looking at clouds and saw odd shaped triangular gap in cloud as if something had punched through it. had an idea to photograph it. thought no more about it until looking at photo later and saw this triangular shadow on/in the clouds hovering right over the garden. huge delta or triangular shape with what looks to be circles to the corners and a short tail. didn't see it whilst sitting there but felt the compulsion to take a photo with my phone. felt very surprised when i saw the photo later. some people i've shown it to can see it straight away and some can't until i point out the shape. they all agree it's weird. i don't think it's imagination.