Shujie is formed in the heartwood of aquilaria trees several centuries after they die when they become infected with a type of mould. Prior to infection, the heartwoo is odourless, relatively light and pale coloured; however, as the infection progresses, the tree produces a dark aromatic resin, called aloes or agar, in response to the attack, which results in a very dense, dark, resin embedded heartwood. On this lot, lines of oud oil can be seen, releasing strong fragrance.