In Lottia pelta, like all limpets, the sexes are separate.  At least in central California spawning may occur throughout the year but particularly between September and  April.  The shield limpet spawns when the surface temperature of the water is between 9 and 15.5 degrees Celsius. L. pelta can spawn about once every two months or, in other words, four times during it's favored breeding period.  

The fertilized eggs develop into a swimming veliger larva with a light weight shell,  foot,  eyes, and tentacles. The velum or veil of cilia propel the larva through the water.   In a related species the larvae settled to the bottom and changed into a crawling limpet like forms after about 6 days.