I don't remember where I read it, so I can't provide a link to give the author proper attribution.

Suppose the MERs roaming around on Mars went their entire mission and didn't find much of interest. Then, one day, they found a spoon.

The implications of that find would be enormous. Not only would it indicate that life once existed on Mars, it would indicate that it was intelligent with metal working technology. That single, simple spoon would have great significance for such a humble object.

In the same vein, that one sarin and one mustard gas shell in Iraq indicates that those weapons once existed there. Saddam never once claimed binary chemical shells in any of his WMD declarations. Unless one accepts the unlikely premise that those two were the only ones built, they both serve as an indicator that chemical weapons were built in at least some quantity.

The fact that the shells didn't have any of the ordinary special markings is interesting from a couple viewpoints. One, that may mean that any number of those weapons could be hidden in plain sight in those massive weapons depots we've found (some of them covering many square miles). In addition, mixing in chemical with ordinary artillery shells is an extraordinarly dumb thing to do, even by Saddam standards.

One last point - we didn't find those shells, the terrorists who're planting bombs did. We have no idea where they found them or how many they may have found.