Pyramid tea bags/sachets
However , pyramid tea bags do not have empty style of tea bags, mainly due to its sealing strategy, you can try to seal pyramid tea bags by seal empty rectangular tea bags, it is very difficult however.
On the other hand, crystal see through rectangular or square tea bag is nice too.
This has been posted before, but maybe a good addition to this thread; http://www.theatlantic.com/health/archive/2013/04/are-tea-bags-turning-us-into-plastic/274482/ I prefer the unbleached paper tea sacs.
Kate said was true, Nylon indeed release it’s molecules into water when the water temperature is above 40 degreeC. There are two type of material has high " Glass transition temperature", its Bio degradable mesh which made from corn extract, or a type of high "glass transition " PET which people calling it environmentally friendly packaging material.