If only Myrtle would pay attention to the Boy's Own Journal, Blackwood's Magazine, etc., she would know that these creatures were Threes, who come from a world let called Threefold on the far side of the asteroid belt. This Threefold is a cheerless, chilly spot, and the whole history and religion of the Threes has been concerned with their quest to knit a nice woolly coverlet for it.

Starcross