Cobalt Shard

Colbat Shards are items that mario and luigi collected in Mario & Luigi: Partners In Time. They were shards, as the name suggests, of the Cobalt Star. Mario and luigi and their younger counter parts, collected these shards, thinking it would destroy the Shroobs. However, collecting all of them would unleash the Elder Princess Shroob. Mario and luigi unwittingly collected them all, and had to go through a vigerous battle with her.