What is the shard in dead space

Hahaha, no, it's called the Marker. It was a giant statue built by an alien race. It emits a frequency wave that affects the necromorphs, so it was put on top of them to keep them on the planet where Isaac ends up in the final chapters. When the Ishimura went down to mine the planet, they found the Marker and took it to study, unknowingly releasing the necromorphs. Isaac is trying to put it back.