Leviathan Souls
From Ratchet & Clank wiki
Leviathan Souls were valuable rare collectible things in the Polaris Galaxy that you could give to the Smuggler in trade for bolts. These souls were released when huge Leviathan creatures were killed.
It was best if players avoided selling them until one reached planet Sargasso to reap the biggest profit from them; 8000 bolts for a soul in normal mode and 800,000 in challenge mode.
