A Time shard is a space-time anomaly, that is best described as a solid piece of time.
Time shards are purple in color. Anything that collides with a time shard risks getting stuck in a disruption of time. In "The Other Side", the Crimson Light suffered this fate when it got stuck inside a time shard, causing time in one half of the ship to pass at a much faster rate than the other half. 60 years went by on the side Little Cato was on in the time it took the rest of the Team Squad to break through the shard and free the ship.
Time Shards are tough. Gunfire didn't even scratch one. It took the combined powers of the Crimson Light's drop drive and Ash Graven to finally break it. When broken, the ship was restored to proper time and the effects of the 60 years age-gap were undone, but Little Cato still remembered the entire period.