[Scatty]

I'm sorry Yoga, I don't know this game, only started it once many years ago.
However this walkthrough should be able to help. Quoting (click on the button to reveal spoiler):

Originally Posted by Walkthrough

After you have defeated the Twyns, rest and heal your
party. Take the stairs up. Here you will find the Guardian of the Rock which
you will need to defeat to get the first ruby eye. Cast Missile Shield and
use Acid Splash/Bomb during combat. Once you have won the RUBY EYEBALL, do
back down the stair and take the opening to the northeast. On this ledge you
will find a closet with a button. The button will open a chute and the area
leading to the PYRAMID.

Spoiler

You can read it up further for yourself in the link above if you'd like to, I better not spoil too much here