Pressure seems to emit from this egg in waves. It pushes away anything drifting through the water and fish seem to avoid it. If you were to try to pick it up, it would be pretty heavy, weighing the egg down so that it doesn't accidentally move itself around.
Serens communicate through sound waves and they are pretty social. This means that the water around them is usually pulsing. Their eyes and markings glow, allowing them to either see in the dark or swim in the dark depths of the ocean but they like to hang around the surface.
Despite the heavy egg, the Seren is a light creature. This is so that when they are near the surface, they can give a swift flap of their flippers and propel themselves to the surface, gliding through the air for a few moments. A Seren's tail can also help them achieve this, though their tails are known more for body language.
Serens are friendly creatures, though they mostly prefer to be among their own kind. Befriending one will not be very hard but you'd have to keep up with their wild personality!