AllSpark Matrix

The AllSpark Matrix was built to hold the remaining fragments of the AllSpark.

Animated cartoon
On Earth, Optimus Prime used the Magnus Hammer to forge the AllSpark Matrix, in order to take the remains of the AllSpark back to Cybertron. He wore it around his neck when he and his fellow Autobots returned home.

The AllSpark Matrix was later used to restore the Blurr cube to his original body.

TransTech
In one universe, Ultra Magnus came to hold the AllSpark Matrix. Rhinox observed this Magnus alongside a variety of other Matrix-carrying Ultra Magnuses throughout the multiverse.