For some reason I havent unlocked the final achievement for unlocking all other trophies. any ideas?

I really didn't get the ending of the game. Morris and Aggi chat about him being loved by the people around him and that is the end? What is with the volcano? They didn't find a replacement for Aggi? Is the island doomed? What was the point of the adventure? Morris not feeling to bad for himself? Or is there a secret ending I missed?...

Just curious if you get anything for collecting them all aside from an achievement trophy. Like an extra cutscene or something.

I just got all the achievements except for the last one. Does anyone know how to get it?

Here's a transcript: I work when I play and I play when I work I can run but don't walk, I have a mouth but don't talk I grow in the winter, I die in the spring I have eyes but don't weep, I have a song but don't sing What am I? Why am I? Why do I exist? Who owns the fish? Riddle me this What is that which belongs to you, but others use it more than you do? What goes up and down the hill, in spite of it all it's standing still? I have streets but no roads, forest no trees, I have rivers no wat...