Possible Clues:

• Group within society with ideas and customs different from the majority
• The ideas and values one expects to find in U-Boats or public transport coming back with most of those in 9 across
• Thread about weird club for particular group within society
• Group customs in U-boats?
• Micro-organism derived from pre-existing one
• Division of society
• Non-mainstream social group
• Group with distinct behaviour within a larger one
• Hip-hop, e.g.