This egg was only available in Egg Cave's Cash Shop Park for September 2011.
Seiren eggs are the most intelligent egg form of any creature discovered in Ark. Shortly after a Seiren egg is laid, it halts the development of the embryo and uses all of its energy to grow a pair of wings on the egg (some refer to them as flippers). After the wings are fully grown, development of the embryo resumes. The wings are then used to keep the egg afloat at the surface of the water (Seiren eggs are laid in water). Seiren eggs need to be immersed in water to develop but must remain at the surface to get oxygen.
Seirens are very quick-witted creatures that live near the bottom of the northeastern seas of Ark. Seirens have developed underwater cities with advanced types of structures carved out of caves and caverns in the ocean's floor. Seirens have even built conductor channels from the vents in the ocean's floor to heat the water in the structures. The last and most stunning thing about Seirens is that they actively catch and trap bioluminescent fish in nets, bottles, and other materials that they can find to light their cities.
In studies that the Science and Research Center in Ark City has done, Seirens are, behaviorally (not genetically ) speaking, the closest living creature to humans.