Collector Trophy in Rock of the Dead
Unlock all extras.
How to unlock Collector
This involves getting all the Picks and Data Crystals "collectibles" in all the levels. All of them are in open areas, and you'll need to strum/hit the notes in-time and without mistake to pick these up. Most levels have two Picks and two Data Crystals. You can refer to the level select screen to see how many you have remaining.