How to get Anima in Final Fantasy X?

I found this online, but it’s pretty long so be sure to print this out and follow the directions closely…

Secret Aeon ANIMA To obtain Anima, a secret aeon and the only way to obtain the Moon Sigil you need to first have obtained the airship. You gain access to the Airship after defeating Yunalesca in Zanakand. Once in possession of the airship go to the hidden area Bajj Temple. When you go there, dive off the ledge to see a short cut scene of Tidus, Wakka, and Rikku. Swim towards the green dot and a fight should appear between Tidus, Wakka, and Rikku. The Boss is Geosangengo or something similar.

Protection against Petrification and Death is vital! If you get petrified you will sink and smash on the sea bottom, thus the character can’t be revived by a Phoenix Down and will no longer take part in the battle. Using Rikku’s technique spare change is an easy way of inflicting plenty of damage especially if you have charged her celestrial wepon to its maximum power. Another tip is, with any boss fight as well, always have the overdrive gauges on top.

Once Geosangengo is defeated you can swim through the door (the green dot mentioned earlier) and you can find the Venus Crest here too. Once inside the door to the hidden chamber follow the path and you will come to a room with a seal in it. If you touch the statues in the room some will light up. Each Statue represents a Cloister of Trails. If you obtained the hidden treasure the Statue’s represent Cloister it will light up. You can re-enter the Cloisters if you didn’t get the bonus item so don’t worry. If you have already have obtained all the hidden treasure chests then the seal will be broken and you can claim your prize!

Once you have obtained Anima you can fight Belgimine’s Anima. Then, if you have obtained the right items you can enter the Magus Sister’s faith. And you can then fight Belgimine’s Magus Sisters. If you defeat them you can send Belgimine to the Farplane, obtain the Moon Sigil and get Yuna’s Celestrial Weapon!