What do you believe the monster in ‘Lost’ really is?

Tell us what you believe the monster is. We want to know what you think.
Update: Yahoo! Answers staff note: Read 'Lost' Producers' reasoning behind choosing the best answer. http://blog.360.yahoo.com/blog-d8pH0dcoRKeB12yOcnUQp.9VCFos?p=19767
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