The Crystal Fragments are objects that appears in Sonic Boom: Shattered Crystal. They are purple fragments of the Lost Crystal of Power which the Ancients shattered into several Crystal Fragments and then hid away to keep it out of the grasp of Lyric the Last Ancient.
One of the objectives in Sonic Boom: Shattered Crystal is to locate all the Crystal Shards.
When the power-mad Lyric the Last Ancient was on the verge of obtaining the Lost Crystal of Power which would give him omnipotence, the Ancients opted to destroy the crystal, shattering it into forty Crystal Fragments which they used on Lyric to imprison him. However, the Ancients knew it was only a matter of time before Lyric would return, so they scattered the Crystal Shards to prevent the Lost Crystal from being reassembled and give Lyric god-like power.
Lyric eventually escaped 5,000 years later and started searching for the Crystal Shards. Meanwhile, Amy Rose had discovered a secret ancient language and manuscript detailing the history and whereabouts of the Lost Crystal of Power's fragments. As such, Lyric kidnapped Amy to probe her mind for information on the Crystal Shards, but Team Sonic put a stop to his plan. During their journey, the team also found all the Crystal Shards and reassembled the Lost Crystal.
One of the side quests in Sonic Boom: Shattered Crystal is collecting all forty Crystal Shards which are hidden in the game's adventure levels. Each level holds a total of five Crystal Shards each and collecting all five will unlock a Sonic Badge. Each Crystal Shard is contained inside a sphere-shaped container with a silver frame and purple screen, which breaks open when attacked or touched and automatically gives the player the shard. The player can then bring the Crystal Shards to Sticks' Burrow where they can be reassembled into the Lost Crystal. Additionally, the restored shards will fill in various spots on the crystal, causing them to glow and also affecting the way the top screen looks during a loading screen.