That’s really interesting. I’m a SoCal native and have never seen one. The Wikipedia article is really interesting, too.

Each “individual” with its sail is really a hydroid colony, with many polyps that feed on ocean plankton. These are connected by a canal system that enables the colony to share whatever food is ingested by individual polyps. Each by-the-wind sailor is a colony of all-male or all-female polyps. The colony has several different kinds of polyps, some of which are both feeding and reproductive, called gonozooids, and others protective, called dactylozooids.