OXNARD, Calif. (CNN) – Thousands of strange sea creatures are washing ashore on beaches across the West Coast, confusing tourists and thrilling scientists.

“The scientific name is Velella velella,” said David Bader, director of education at the Aquarium of the Pacific in Long Beach, California. “They’re jelly-like creatures, but they’re not exactly jellyfish.”

The creatures have a clear, distinctive fin sticking up from a blue, oval body no larger than the palm of your hand.

“Every now and then, the currents and the winds will change and these guys will, instead of being pushed out to sea, they actually wind up on the beach,” Bader told CNN.

Experts say the creatures, also known as by-the-wind sailors, sting but humans shouldn’t be concerned.

“That sting is not very potent. It’s nothing that could actually get through my skin,” Bader said.

Velella velella feeds on plankton and fish eggs caught with tentacles that hang down from its jelly-like body.

The creatures float on top of the ocean with their fins sticking straight up so they can flow with the tide.

“Out at sea, they look like bubbles on the surface of the ocean until you get up on them,” said Julie Bursek, of NOAA’s Channel Islands National Marine Sanctuary.

“A lot of people probably never knew an organism like this existed in the world,” Bader said. “And you know the winds change, and all of a sudden they wash up on shore and we get to see what the ocean is really made of.”