Walking past the main pond, my eye was caught by a striking pattern reminiscent of a brain coral. Lying down on the boardwalk to get the diminutive lens of my phone camera as close to the pond surface as possible, the squiggles resolved themselves into long patterns of jelly divided mostly into hexagonal areolae like miniature cells in a honeycomb, each with a white boundary and a tiny yellow egg at its centre.

At the top left of the photo is a large Ramshorn Snail: several others were nearby, so they are the likely culprits. Generally pond snail egg masses (as laid by the large pointy-spiral pond snail Limnaea) are small, undistinguished jelly-blobs, so these large, impressive structures were a surprise.