Interestingly, EJ Wilson discovered this on a large jpeg image which NASA had up - and EJ says they have since removed it and it is no longer available to the public. The jpegs in its place are much worse images. Only the individual sol shot is better:
Last Edit: Aug 18, 2012 10:22:15 GMT -5 by Marsrocks
This intriguing image below from Gusev crater is of an object which is extremely similar to a spine. It was discovered by Mars Anomalies member, convex: