This is a boulder at Moeraki which is about 2 hours south of Christchurch. There’s a whole bunch of them along the shore line. They are very cool. They look like aliens left them here! They’ve been formed due to corrosion – see http://en.wikipedia.org/wiki/Moeraki_Boulders for a better explanation than I can give! If you are ever in the vacinity you MUST see them, there’s something quite spiritual about them.