Our selection of sunglasses have one major thing in common. Bamboo. I'm sure you already know that bamboo is an incredibly fast growing plant, so that makes it very sustainable. In fact Certain species of bamboo can grow 910 mm (36 in) within a 24-hour period, at a rate of almost 40 mm (1 1⁄2 in) an hour (a growth around 1 mm every 90 seconds, or 1 inch every 40 minutes. How cool is that.