I'm stuck in one of the first areas. The odd Naija-like creature showed me the 'vision' already and I went to the next area, I passed a red stone and saved my game. I think this area is called Secret Cave Passage. I can go through one area but it is just a big dead end. If I go back I can't find any other routes to take. There's a bunch of violet coral and the skeleton of a .. whale? .. There's also some of those colored plants you can sing to, that when you match their color give you items. I see what looks like an exit but a big boulder blocks the way. I assume I need to do something, get some song, etc. to clear it but I can't seem to find it

I think I missed some important tip the game gave me.
Also, what if anything is the function of the small and big jellyfish? by big, I mean the HUGE one with the little sphere in the middle of it. Sorry for how vague this post is. So here is a screenshot to help
http://img525.imageshack.us/img525/5529/secretcavepassagebv1.jpgThanks very much for any help!