Ecco DotF Easter Egg: Tesseracts in Hanging Waters Cubes

This is a REALLY well hidden Easter Egg in Ecco the Dolphin: Defender of the Future. It works in the Dreamcast and PlayStation 2 versions of the game. How to perform: 1) From the start of the level, jump into the water bubble to the right with the glyph. Swim as close towards the volcano as you can (without falling out of the bubble of course). 2) The hidden object is at the top of the volcano! Sonar towards it at multiple angles. Fine tune the sonar direction by tapping the analogue stick. When you h