The ancient Egyptian Scarab Beetle was a symbol of death and rebirth. The reason they associated it with reincarnation is because of the dung beetle's behavior. It's actually quite a fascinating sight to see!
A female dung beetle lays its eggs in, well, dung... It then rolls the dung on the ground until it becomes a smooth ball.
This becomes not only the shelter for its young, but also provides them with food when they hatch.
As the ancient Egyptians observed it, they saw the ball of dung as agolden sun being pushed along the sky by a beetle. It was hot, and also became a source of life as the new beetles emerged from it.
Not only that, but when the female beetle died, it seemed as though she was reincarnated from this golden sun, with the new beetles coming out of it as though she was reborn.
These born-again beetles were then worshiped as "Khepera" or"Khepri" (the Scarab), meaning "he who came forth". They represented the sun at dawn, as it was also the young sun that came forth after night.
As you can see, the ancient Egyptians loved to connect any act with that of the cycles of life, death and rebirth. Anything that could confirm their desire for an afterlife was of course used symbolically in their depictions of deities too!
If you see some of the depictions of The God Ra , he is sometimes shown with a Scarab for a head. His name when in this form was Ra-Khepri.
As with most of the ancient Egyptian symbols of protection and religion, the Scarab was used in amulets to be worn by the living or deceased. Take a look at this collection of ancient Egyptian style jewelry from amazon, it includes scarab jewelry.
Another important use for them was when they were used as "Heart Scarabs". These Scarabs had certain parts of the Book of the Dead written on them then placed over the heart of the deceased. This would ensure that the heart would not give away the deceased’s secrets during final judgment by Osiris that could be held against him/her.
Can you believe how much mythology surrounded such a tiny creature? And who would have thought that a being that deals in dung would achieve sacred and holy status? Strange but true!