Spider

I've never come across what I think is a spider's nest that looks as distinctive as this before. And yesterday I saw a couple of these, identical type of white, almost cocoon like casings (for lack of a better word) hanging in this Yew, suspended in the middle of two long guy-wire type webs. Only one of them had a spider under it, hence I think it's a spider's nest of some sort. Sorry the focus isn't the best.