A Borg auto-regeneration unit in 2375.
An auto-regeneration unit was a Borg device made of a polytrinic alloy. It was spherical in shape and could crawl around on its own autonomously even after its ship was destroyed.
An object suspected to be a functional auto-regeneration unit was among the technology salvaged from the debris of a Borg probe destroyed by the USS Voyager in 2375. Captain Kathryn Janeway initially mistook it for a transwarp coil, until Ensign Harry Kim warned her not to touch it. (VOY: "Dark Frontier")
The prop representing the auto-regeneration unit was previously seen in "The Nth Degree" as part of the Cytherian-influenced Human-computer interface that Reginald Barclay builds, as well as in the Voyager episode "Thirty Days" where it served as Riga's depth sensor. Later the prop would appear in the armory of the Enterprise NX-01 (ENT: "Silent Enemy", ENT: "Sleeping Dogs"). It measured 50 inches in circumference with a height of approximately 8 inches and comprised a silver-colored sphere featuring copper-colored trim, attached by grommets, dividing it in half and then dividing those halves into quarters; each quarter had a circular interface with a roughly pentagonal housing in the middle connected by a single screw. The prop was later sold off in the It's A Wrap! sale and auction for US$607.62. [1](X)