With this jam jar from the Japanese brand Aohata, the lid closes by itself as if by magic.

As soon as it is placed loosely on the glass, it automatically turns in and can no longer be lifted off. Only a little force is then required to close the jar tightly.

Anyone who suspects that a magnetic force is involved here is wrong. Both the inside of the metal lid and the glass thread of the container do not initially differ from conventional containers. The answer lies in the glass ribs of the thread: They are inclined at a steeper angle than the ribs on standard glass jars. This makes it easier to overcome friction and the lid slides downwards like an object on a steep slope.