This egg isn't an egg at all; it's a snowglobe. It rests on top of a bit of snow mixed with toxic goo that's presumably from the Science and Research Center in Ark City, which will eventually become the snail that grows beneath it.
Heimurins exclusively live in the wet snow. They cannot live outside of snow. In the summer months, this means that they retreat to the mountain peaks of Ark that stay snow-covered year-round. In the winter months, however, they love coming to snowy Ark City and spreading their Christmas cheer.
Heimurin snowglobes each show a different and unique holiday scene. Some Arkians shop for months on end to find the perfect "Heimurin Scene" that showcases and represents their personality. Some Heimurins have even become collector's items. If yours happens to be a collector's item, spoil them all you want and, most of all, keep them cold (refrigerated) and in a bed of snow crystals.