Related Clues:

• Accommodation for prisoners
• Phones in pockets or purses
• Small rooms
• Rooms behind bars?
• Honeycomb components
• Biological building blocks stop oxygen being withdrawn from instruments
• Subversive groups that research challenging academic subjects?
• Rooms at Stony Mountain
• Pen divisions
• Sudoku's little boxes
• Check rooms in monastery for controversial sources of therapy
• Biological units
• Building blocks of life
• Amoebae, e.g
• Basic units of life