Most commonly in the form of a flaky or smooth chocolate ball or traditionally a truffle-shaped lump, Belgian chocolate truffles are sometimes in encrusted form containing wafers or coated in a high-quality cocoa powder. They contain a soft ganache which is traditionally a semi-emulsion of liquid and therefore has a couple of days' shelf-life at low temperatures and/or requires refrigeration. Special truffles sometimes have a fruit, nut or coffee ganache.