Cholla Wood is one of the most useful accessories for shrimp tanks. It is a softwood that provides a food source for biofilm that shrimp will feed on, similar to what leaves do. The chollas provide hiding places for shrimp after they molt or when they are feeling vulnerable. The wood will eventually break down and disappear but it will take at least a year for the thinnest pieces and much much longer for the thicker ones. There are 2 different species of Cholla: Stick Cholla and Teddy Bear Cholla. This product is a Stick cholla which is suitable for normal or small, nano shrimp tanks. Our chollas were treated carefully before selling to customer to ensure 100% chemical free, 100% harmless to shrimps/snails/fish. However customer still need to rinse it before putting it in a tank. The dry cholla can float on the water surface in few days before absorbing enough water and sinking.