OMG Mia I just had the same conversation about bioluminescent creatures! DH and I went to Vieques Puerto Rico http://www.biobay.com/ just to swim with these critters, long before DS was born.

I'm fairly certain that DS knows there is no Santa but he loves the idea of the magic. He gave me that "look" last year when he asked how Santa gets out of our fully enclosed gas fireplace and DH told him there's a fingerprint sensor on the inside for Santa to open the glass. Probably a stretch on DH's part!