Moulds can be on the surface of cheese or be developed internally. Surface moulds are the result of cheese being treated with the Penicillium candidate spore; internal moulds are created by the introduction of Penicillium glaucum or Penicillium roqueforti spores both to create blue veined cheeses. Certain French goat milk cheeses develop a natural bluish surface mould and some of the newer double creme cheeses have both a surface mould and an internal mould e.g. Blue Castello, Bavarian Blue, Duet.