Small, light-blue marine creatures are washing up by the millions on beaches and shores from Oregon to California, for the first time in years. These mysterious jellyfish-like animals are attracting tourists, who are traveling to see the unusual creatures.

Velella velella is a distinctive creature, and is the only species in its genus. They are a form of hydrozoa, a type of small, meat-eating animal, related to jellyfish, that usually lives in salt water. Other lifeforms in this class of animals are freshwater jellies and the Portuguese man o' war.

Velella velella live on the surface of the ocean, and possess a crest that runs along their bodies, which can act as a sail. Winds blowing onshore could be responsible for the animals coming onto the Pacific coast, according to researchers. Velella do not have fins, tails or other means of locomotion, so their travel is directly solely by currents in the water and wind.

Jelly fish swim underwater, while velella float, using tentacles to reach for plankton underneath the surface. They reach a maximum diameter of about three inches across.

"If you pick these guys up and put them in the water and look at the underside, (you'll see) these tiny little tubular polyps and tentacles and other sort of things, which is the living part of the animal. If it isn't face-down in the water then they can't make their living - they'll dry out on beach quickly," Jim Watanabe from the Hopkins Marine Station, managed by Stanford University, said.

Stings from velella are powerful enough for the creatures to capture their prey, but they are barely felt by humans. This means deposits of their bodies do not pose an immediate health risk to people. Some of those who touch the creatures can be sensitive to the toxins in velella, but washing hands and face after exposure removes most of the chemical from skin.

Biological classification of the species is challenging. Many biologists now believe valella should be thought of as a collection of separate polyps, primitive lifeforms, shaped like a cylinder.

The bright blue, symmetrical design of velella almost makes the deposit of creatures look artificial.

"At first, I thought that a container ship may have spilled hundreds of plastic blue reflectors in the ocean... These forms were stacked with perfect concentric circles that looked machine-made and topped with a rubber-looking flap that may have belonged on a bike," Andrea Hackman, a photographer who witnessed the event, wrote.