Found thousands of these translucent blue, plastic-looking ovals washed up on the beach today. They have a stiff fin on top and blue jelly underneath. Are they dangerous?

If you’ve strolled along a beach and come across thousands of translucent blue ovals that resemble plastic debris, you may have stumbled upon one of nature’s fascinating phenomena. These creatures, known for their unique appearance, have sparked curiosity and concern among beachgoers, often causing alarm due to their unfamiliar presence.
While their vivid blue hue and unusual shape might resemble marine debris, they are, in fact, living organisms. This article delves into what these creatures are, whether they pose any danger to humans or pets, and why they occasionally appear en masse on our shores.
1. What You Found: Meet the By-The-Wind Sailor
The creatures you’ve encountered are called Velella velella, commonly known as “By-the-Wind Sailors.” They are a type of hydrozoan, closely related to jellyfish, and are part of the phylum Cnidaria. Velella velella typically measure around 7 cm in length, with a distinctive triangular sail that helps them navigate across the ocean surface. Their vibrant blue coloration makes them stand out against the sand when they wash ashore.
These organisms are colonial, meaning they are composed of a group of specialized polyps that function together as a single entity. Each Velella has a stiff, translucent sail that protrudes from the top, allowing them to catch the wind and drift across ocean currents. Underneath this sail lies a gelatinous body that is home to their feeding and reproductive structures.