[Don Joe]

I thought the horseshoe crabs were more related to spiders, scorpions and the now-extinct eurypterids (thankfully extinct, because some species were like 15-foot upside-down swimming scorpions). Horseshoe crabs are in the order Xiphosurida, sort of all by themselves taxonomically. I seem to recall they had "blue blood" ... is that true?

From the first link I grabbed via google query for "horseshoe crab" trilobite, "a Horseshoe crab is not a trilobite,but it is the closest living relative of the trilobite." (http://community-2.webtv.net/mrbbug2/doc2/)

(In the past, I've read in numerous places that they're related, so I just grabbed the first reference for this reply. As to the blood color, I've no idea. My mother never let me keep any of 'em I found at the beach when I was a kid. :)

[Brett66]

I think it would be more honest for NASA to say "yes this could be life, but we can't say definitively until we send another probe specifically designed to get the proof that we need."

[NormsRevenge]

Thanks for all the info and links.