These are great to use as hides for shrimp, small fish, isopods, slings and other terrestrial invertebrates.
 
In the aquarium they slowly breakdown releasing tannins and growing biofilm.
 
Tannins help lower the pH of your water, They have also been shown to have antifungal properties.
Biofilm is a great source of food and grazing for shrimp.

For use in the aquarium we recommend boiling them for approx. 30 mins then soaking overnight to help soften them then squeeze underwater like a sponge so they can sink.
 
Due to being a natural product size and shape will vary.