A box of coins

When I first moved here 4 years ago, I used to hear strange sounds very late at night. I used to stay up late after everyone else gone to bed. I spent time doing some reading, watching TV or just browsing the internet, and it was gone midnight. I used to hear noises coming from the locked shed in the garden, it sounded like something heavy moving around. One day I went into the shed and couldn’t find what made the noises. There was a pile of bricks on the floor in a corner, left by the previous owner, I happened to shift them a little and they made the exact same sounds. Weeks later there was a hidden box inside a niche above a shelf.It was full of old foreign coins and must've been there in the shed for a very long time. After the discovery of that box of old coins, the noises at night stopped, and I haven't heard it ever since.