Summon forth your albino karakul, a black sheep among its kind. Which is to say it's white.
Though karakuls ordinarily have black fleece, this creature raised in the paddocks of House Haillenarte was born snowy white. This rarest of qualities spared it a fate at the dining table, and it grew to such a size as to be able to bear people upon its fluffy back.
A wise knight keeps her own source of wool. - Yaelle