This fruit attracts birds with an unusual way of making itself metallic blue

Instead of relying solely on pigments, the metallic blue fruits of Viburnum tinus use structural color to reflect blue light, a mechanism rarely seen in plants. Researchers show that the fruits use lipid nanostructures in their cell walls, a previously unknown mechanism of structural color, to get their striking blue -- which may also double as a signal to birds that the fruits are full of nutritious fats.