pebble, n.All

Some penguins participate in prostitution, performing sex in exchange for pebbles.

Penguins are real romantics --- Gentoo penguins propose to their life mates with a pebble.

Atoms are so tiny that an atom is to a pebble as a pebble is to Mt. Everest

The Pebble is harder to break than the rock.

The Pebble is harder to break than the rock, much like the child and the adult.