Spotted in the pond sat on the frogspawn

Any ideas? It almost looks like a huge eye ball, there are 4-5 out there.

Extras show Rory and Jack, they hurtled around the garden as I wandered, it was good to see Jack climbing the tree and Rory playing on the horizontal trunk. And of course more crocus. Think I prefer them in groups and may move some of those planted later last year, they are fairly ineffective when dotted in the garden