This egg was only available in Egg Cave's Cash Shop Park for February 2014.
Purita eggs emit a high-frequency, inaudible sound (the frequency is well beyond the scope of human hearing) that stimulates the auditory cortex of the human brain to produce emotions of happiness and serenity. When a Purita hatches, some people say that they experience feelings of sadness and loneliness (presumably because of the loss of these inaudible sound waves) but do quickly adapt to their newly-hatched creature.
Puritas are fun-loving creatures that are capable of producing a number of strange sounds, some even not perceivable by the human ear. Some Purita sounds are funny, others are hysterical, a few are scary, with a small number being quite repulsive. However, Puritas both know, track, and remember the sounds that their owners respond to positively to, so with simple conditioning that occurs naturally, they end up making their owners very happy with their strange noisemaking abilities.