Not a shamrock
I took this photo earlier this summer and finally decided to post it. This old pan had been left outside and filled with rain water. One morning I noticed this green, symmetrical, segmented mass floating in the water. In fact there was a bunch of them stacked like Life Savers in a pack, without the wrapper. I'm guessing they are some kind of egg mass? If anyone knows what this is, please let me know! I thought it was quite beautiful and mysterious against the pan.