Related Clues:

• They're often barred in reception areas
• Barred rooms
• Jail units
• Accommodation for prisoners
• Phones in pockets or purses
• Small rooms
• Rooms behind bars?
• Honeycomb components
• Rooms at Stony Mountain
• Pen divisions
• Sudoku's little boxes
• One-celled critters
• They're often seen on slides
• Biological units
• Building blocks of life