Massive numbers of by-the-wind sailors spotted on California beaches.

Millions of Velella velella, also known as by-the-wind sailors, have washed ashore along Southern California's coast this week. Experts say this is a natural phenomenon caused by ocean currents and wind patterns. These hydrozoa feed on plankton and have a small sail that allows them to travel great distances across the world's oceans. They carry a toxin and have very little meat, making them unappealing to predators. The creatures will either rot away or be pulled back into the ocean by the tide.