Pharos Subterra

[PuPu]

No, just look for certain treasure chests in certain areas.

Here's a map:

http://www.gamefaqs.com/console/ps2/file/459841/45695

You put the Black Orbs on the pedestals in the rooms in the corners of each floor. Once you put enough Black Orbs on the pedestals, the room will light up. However, if you do end up putting too many Black Orbs, they will be wasted. Once you put enough Black Orbs on every pedestal on the floor, the next floor will be unlocked until you get to the floor "unknown," which can only be unlocked once you have accepted a certain Mark hunt.

The monsters in the outer ring where the elevator is don't drop Black Orbs, so it's pointless to fight them. Also, in the rooms on every corner, there's a chance that if you don't pick up the Black Orbs that the monsters drop and that you let them float away, they will stockpile into a Massive Black Orb, containing three times the amount. Basically, if you kill 10 monsters that drop Black Orbs, let them float away, and find the Massive Black Orb, you will get 30 Black Orbs. However, I think the Massive Black Orb can only appear once for every time you enter the area.