This egg was only available for Halloween 2014.
Horsekin eggs emit a strange green flame. The flame itself is not hot nor does it burn anything. However, any object it touches will glow in the dark for a short period of time.
The green flame that once emerged from Horsekin eggs now sprouts from the young Horsekin as its mane and tail. This flame starts out small and uncontrolled but as the Horsekin grows it is able to consciously grow and control the flame. One notable aspect of this is the ability to separate some of this flame from their bodies, placing it in some sort of container, usually a jack-o-lantern. This allows for manipulation of the container with out the Horsekin having to touch it. Many Ark citizens will use Horsekins in their haunted houses since, along with their ability, Horsekins enjoy spooking people. There is nothing malicious in this behavior; a Horsekin who accidentally scares someone too much is usually the first to try and comfort that person.