Porpita porpita, commonly known as the blue button, is a marine organism consisting of a colony of hydroids found in tropical and sub-tropical waters. Although it is superficially similar to a jellyfish, each apparent individual is actually a colony of hydrozoan polyps. The blue button is a Chondrophore, which is a group of cnidarians that also includes Velella and Porpema. A couple weeks ago the wind was blowing these up on the beach and I got a few photos. They are only the size of a quarter.