What is it? Clio recurva is a floating sea snail from the group Pteropoda, which literally means “wing footed”. Their snail foot has evolved into two wings with which they fly through the water like butterflies in the air. They float together with other plankton in ocean currents, never touching the ground. 
Clio recurva builds an incredible, thin yet strong transparent shell out of calcium carbonate, which protects them against predation and infection. But sadly, this carbon-storing ability also makes them vulnerable to ocean acidification; increasingly acidic seawater can dissolve their shells.

Where do they live? This species has been reported from the north Atlantic and Pacific ocean basins. They are probably more abundant than we think, because they occur deeper than most other planktonic snails (below 300 metres deep). 

What do they look like? They don’t look at all like your typical snail! The shell of C. recurva is wavy and triangular shaped, like a partially flattened ice cream cone. They can be up to 3 cm long, and have been traded by naturalists as prized possessions.
Clio recurva is a “mucus feeder”, meaning that they produce a sticky mucous web similar to a parachute to snag passing particles and other plankton. Their shell is often covered with hydroids that enjoy a free ride through the open ocean, but we don’t know if this is harmful for the snails or even beneficial because it may help them float. 

What secrets will this genome reveal? Its genome will tell us how they build such an extraordinary shell, which is unique in the animal kingdom, and may be useful for us to design new materials. Because their shells are extremely vulnerable to ocean acidification, sea butterflies are used as indicators of the impacts of changes in ocean chemistry. Knowing their genome will be important to understand their ability to adapt to the rapidly changing ocean.