Slytherin house values ambition, cunning, leadership, and resourcefulness. The house mascot of Slytherin is the serpent, and the house colours are green and silver. Salazar Slytherin founded the house. The Head of House is Severus Snape until near the end of the sixth year. Then, Horace Slughorn, the previous Head of House, comes out of retirement re-assuming authority. The ghost of Slytherin house is The Bloody Baron. Slytherin corresponds roughly to the element of water. The Slytherin dormitories and common room are reached through a bare stone wall in the dungeons. The Slytherin common room is a long, low, dungeon-style room, under the Hogwarts Lake, furnished with green lamps and carved armchairs.