Biology/Natural History: This species grazes on algae and also on hydroids, bryozoans, sponges, and other small animals. It feeds mainly at night and on foggy or cloudy days. Eggs are about 0.2 mm diameter and gray-green. Larvae swim freely after hatching, developing all 8 valves. In CA they settle about day 8 and metamorphose to miniature adults by day 16. Adults grow about 11-40 mm per year. Predators include the ochre seastar Pisaster ochraceus.