Actually Matoran being aliens would make sense because in Bionicle Mask of Light (the movie) at the start Turaga Vakama was telling the tale of the Matoran; In the time before time on the mysterious island of Mata Nui, the Great Spirit descended carrying we called the Matoran we were seperate without purpose, so the great spirit illuminated us with the three virtues: unity, duty, destiny. And in gratitude named our island home Mata Nui after the Great Spirit himself. But our happiness was not to last, for Mata Nui's brother the Makuta was jealous of these honors and betrayed him, casting Mata Nui into a deep slumber. The Makuta was free to unleash his shadows and unleash them... he did. Woe, got a little off topic there, but you get the idea...and if you don't than I will tell you. The idea was that the great spirit descended, from where, another planet such as Bara Magna which has a similar species type?!