Omnitrix (ExOS)

The Omnitrix is a DNA altering device, currently in the possession of Ben Tennyson.

History (Before ExOS)
Sometime prior to the events of the Original Series, a Galvan named Azmuth created the Omnitrix with the purpose of bringing the beings of the universe closer together. With the help of his assistant Myaxx, he gathered DNA samples from all over the galaxy and stored them within this device.

At some point, information about the device leaked to the far corners of the galaxy, causing Azmuth to go into hiding on a planet called Xenon, to avoid the onslaught of alien scumbags trying to get ahold of it. One notably being the infamous warlord, Vilgax.

When the device was completed, Azmuth found himself unable to transport it anonymously, so a transporter named Xylene was contracted to transport the device to its intended location.

However, Vilgax was able to track down Xylene and fired at her ship. Luckily, she was right over her destination when she emergency jettisoned the Omnitrix: Earth.

On Earth, the Omnitrix landed near Yosemite Park in California and was intended to go to Maxwell Tennyson, being one of the greatest known Plumbers who ever lived. However, an individual with similar enough DNA was who it landed near. Max's grandson, Ben Tennyson. And the rest is history.

Presently, the Omnitrix seems to have changed in appearance as Ben's aged, and as he continues to unlock aliens.