Much like Sylvern eggs, Ulumin eggs only appear during rainstorms. However Ulumin eggs can be found floating much closer to the ground, about a foot or so off it. These eggs always hatch during gentle summer rain storms.
Ulumins are happiest when its raining. When its not raining Ulumins are confined to walking on the ground. While they have no problems walking, or even running, Ulumins prefer floating and flying. An Ulumin will begin to float as grey rain clouds begin to cover the sky. Once the first raindrops fall the floating will turn into flying and the Ulumin will happily spend the rest of the storm playing amongst the clouds and falling rain. Once the rain ends many Ulumins can be seen drifting slowly back down towards the earth where they will wait patiently until the next time it rains.
There is some speculation among scientists at the SAR Center that Ulumins have the ability to conjure rain storms. This is due in part to the fact that Ulumins can be seen gathering together in large groups before rain clouds even begin to form. It has not yet been determined if they are actually doing something to bring about storms or if they can just sense storms before they start to form.