In space, there are clouds that contain gas and dust ejected from stars. Our solar system was formed 4.6 billion years ago from such a molecular cloud. Most of these dust grains were destroyed during solar system formation. However, a very small amount of the grains survived and remained intact in primitive meteorites.

They are called presolar grains because they predate the solar system. I am a scientist who studies the early solar system and beyond, focusing mainly on presolar grains.