Progress down the hall as he comes and goes, then speak to him at the end as he reveals what he really wants to do.

The upcoming chamber contains the hieroglyphs Sephiroth was looking at before. Make sure nobody has any fire element effects on their weapons. After that, have it heal you, save, and enter the hole on the far right to return to the newly opened door. If you find that the creature has jumped up a level and you're on the bottom floor, enter the hole on the far left to catch him for good. Pay attention to which hole leads to which: The hole he comes out of depends on which hole he enters from. Run through the same tunnels he does, and when he drops to a lower level, do the same so you can continue after him. The next room is a set of tunnels with another purple creature running around it. VII leads to a Trumpet Shell weapon for Cait Sith even though you probably don't like him very much right now, he'll be sticking around for a while. There aren't a whole lot of these in the game because of its powerful effect: It protects the wearer against all negative effects. V leads you to the chest outside in the large, path-y room, which has a ribbon in it. In IV is the Princess Guard, Aeris's strongest weapon. Depending on whether you want to continue enhancing your currently equipped Materia, consider holding onto this weapon for later use. Make sure you also drop off the clock for a battle by getting hit with the second hand as it passes by, as this rewards you with a strong but Materia-less weapon for Cloud. The only rooms you need to go into are IV, V, and VII before continuing on. The next room is a clock with an hour, minute, and second hand. Once through, Aeris will have the group turn back to the purple pool of water halfway through the hall so she can listen to the consciousness within.

Make sure you're not running the game at 3x speed so you can actually get through this hallway. When you get to a room with rolling rocks, you should notice that there are gaps for Cloud to stand in without getting squished.

Final fantasy 7 city of the ancients