Related Clues:

• Matter for the gray matter
• Head light?
• It may be glassy or icy
• It's formed in your head
• Piece of property
• See stars, maybe
• Valued property
• Birth of a notion?
• Brain product
• Glimmering
• Think tank nugget
• Embryo of an invention
• It's in your head
• Clever thought
• It's a good thing