This pretty rock snail was about 2" long, found under a rock with dogwinkles and isopods in the lowest intertidal zone during a minus tide. The ridges on its back are unusual. They don't seem deeply grooved enough to be a Leafy Hornmouth.
Here are 9 Nucella lamellosa or Frilled Dogwinkles, and masses of their egg capsules, each of which contains up to 80 eggs. The eggs are known as "Sea Oats," and look a bit like honeycomb when freshly laid. As they age, they seem to darken to a purplish or browning color. The Nucella lamellosa is usually an inch or so long, but a few grow to about 3" or bigger.