That reminds me of bismuth crystals: http://www.google.co.uk/images?hl=en&source=imghp&q=bismuth+crystal http://www.google.co.uk/images?hl=en&source=imghp&q=..

That reminds me of bismuth crystals: http://www.google.co.uk/images?hl=en&source=imghp&q=bismuth+crystal http://www.google.co.uk/images?hl=en&source=imghp&q=... I think that is a result of it being one of the few substances other that water that has a liquid phase that is denser than the solid.