@Gordana 9 April 2021 more from that month

Glaucus atlanticus, better known as the Blue Dragon or Sea Swallow, is a species of small sea snail in the Glaucidae family. Growing about 3 cm, they can be found across the world’s oceans in temperate and tropical waters. In addition to its unusual appearance, the Blue Dragon has also developed an unusual way of moving. There is a small bag of gas in their stomach that allows them to float along with the waves - and that's it. The only mode of transport for these sea snails. Due to the blue color on the stomach, and the silver color on the back, when the Blue Dragons float upside down, they are almost invisible both from the depths of the sea and from the air. When they are on land, they curl up and spread again only when they enter the water.