These are pistachio shells! Hot-glue a second row of shells outside the first, keeping them flat and tucking them between the first row. Finally, hot-glue pistachios to the metal around the candle and place it in the center.
Love Birds from Pistachio shells
Not sure if I would have the patience for it ;)) DIY: Hanging “Succulent Garden” Made With Pistachio Shells
I knew I there should be a use for all those shell halves when I ate the "Roasted No Salt" from Valley Pistachio in Madera Ombre Necklace Made from Pistachio Shells – DIY
DIY and Crafts: Easy Pistachio Flowers - Sweet for Mother's Day