The Clock at The Burrow is a magical clock that doesn't tell the time. Instead, it has things such as "Time to make Tea".
From the Story
Discovered in Book 2, Chapter 3, The Burrow
"With only one hand, this clock is not much use if you want to tell the time but very useful in other ways. It points out when it is time to do something like 'feed the chickens', and it even knows if you are late."