This is an old coin cache! It's a small containor with a handful of coins inside. The idea is once you find it, you take a coin to keep for yourself, and leave a coin that is at least 1 year older, so make sure to bring a handful of change with you on your hunt! You can take a quarter and leave a nickel or take a dime and leave a silver dollar, it's up to you! The whole point is that the longer this cache remains and the more people that visit, the older the coins will become. Have fun!