"If more data confirm Eros is primordial, Eros will be a link between the chondrite meteorites found on Earth and the history of the solar system's formation, " McCoy said.

CNN: Asteroid Eros resembles 'building blocks' of Earth

Asteroid 99942 Apophis is a primordial relic from the formation of our Solar System.

BBC: Foresight mission spacecraft Image

Evidence that the sun was once part of a brood comes from the rubble leftover from the formation of the solar system.

FORBES: Searching for the Siblings of the Sun

The perceived problem is that for the first 600m years of its existence, the planet was being bombarded by bits of debris left over from the formation of the solar system.

ECONOMIST: The origin of life

But one of--a major constituent of comets, we believe, are stardust, interstellar grains, particles that formed 'round other stars and were the original seed of the star formation of the solar system.

NPR: Stardust Set to Deliver Comet Samples

If the moon harbours ice, for example, measuring the amount of it at different depths could enable planetary scientists to work out the rate at which comets smashed into the lunar surface over its history, and that knowledge could then be plugged into models of the formation of the solar system.

ECONOMIST: Divining water