Identifying Small Glass Tubes Containing Three Tiny Ball Bearings: What Could They Be?

try to open a sealed glass tube simply to investigate it. Older glass can be fragile, and the contents may not be suitable for handling.
How the metal balls move

Without shaking or applying force, carefully observe what happens when the tube is gently tilted.

Do all three balls move freely?

Do they stay together?

Does one ball move independently?

Are there internal stops or partitions?

Do the balls appear magnetic or attached to anything?

These observations may help distinguish a loose-ball component from a sealed assembly or decorative object.
The material of the balls

The spheres may be steel,