Frog spawn mystery

I awoke this morning to find a big clump of frog spawn had been dragged from the pond and was on the path nearby. (Approx 7.30am) The pond is slightly raised 30cm from the ground, and the water level about 8 cm from the top of the pond

The spawn had been dragged out over the wall (wet patch visible) and the clump was on the ground nearby, stretched away from the wet wall. (trailing water patch visible). When I had observed this clump a couple of days ago, it appeared to be about 15 cm at its longest point).

This was the only clump of frog spawn near the edge of the pond that was completely submerged and free floating. The other clumps of spawn, easily accessible from the vegetation had been laid partly on the vegetation and stuck fast (I tried to move them into the water, but could not dislodge them without fear of damaging the eggs).

Any ideas! My thought was a fox; we do have foxes that pass through our garden late evening and early morning. We also have lots of cats around this way and they do take a lot of interest in the pond, but do little more than dip their paw in - and not really enjoying the sensation. We also have lots of herring gull, but I can't imagine them being able to drag a clump of spawn out either.

The spawn still looked fairly fresh and the water patches had not dried up, so it must have happened. I managed to pick the clump up carefully using a dustpan and put it back in the pond.