A magical device that could be used to store and review memories, the Pensieve was a rare artefact used by advanced witches and wizards. A shallow stone bowl carved with runes and symbols, the Pensieve could be filled with memories that appeared like a silvery vapour, which other people could then view. Due to the personal nature of peoples' memories, most Pensieves were well protected and then buried with their owner. However, Harry Potter entered many Pensieve memories with Dumbledore's help during his research of Lord Voldemort. Hogwarts has its own special Pensieve, used by a long line of headmasters and headmistresses, including Dumbledore.