This week’s beach walk brought one of the strangest and most fascinating treasures of the spring season, long strands of lightning whelk egg casings washed ashore. Some stretched nearly three feet long, twisting through the wrack line like pale sea serpents. At first glance, they hardly look alive. But tucked inside many of the jelly-filled pods were tiny developing snails, each no bigger than a grain of rice. By carefully opening a few capsules…