[1][2] Born in Dannevirke circa 2008,[3] he was named after All Black Sonny Bill Williams.
The prediction process was designed so that Sonny Wool was presented with two boxes containing feed in the form of hay, each box marked on the outside with the flag of a national rugby union team in a forthcoming match.
His choice of which hay to eat first was interpreted as indicating his prediction of a win for the country whose flag was on that box.
Selections by the sheep were correct in all of New Zealand's matches in the 2011 Rugby World Cup,[6] though predictions for the other three quarter-finals turned out to be incorrect.
His manager described him as "a bit socially inept" who prefers the company of humans and has "got a few fetishes for things – one is light at night and he really likes rugby balls".