 Druids have participated in other musical genres and with more technological instruments, including the blues and rave music, and one British club, Megatripolis, opened with the performance of a Druidic ritual.Among many Druids, there is a system of tree lore, through which different associations are attributed to different species of tree, including particular moods, actions, phases of life, deities and ancestors.Different species of trees are often linked to the ogham alphabet, which is employed in divination by Druids.