[PatrickHenry]

... difficult, if not impossible in that the objects pictured could either be the result of physical/chemical necessity, or they could have been caused by an intelligent agency mimicing physical/chemical necessity ...

Request for clarification:
Are you definitely saying that there are cases -- such as #9 -- where nature could look so much like design that it's impossible to distinguish between the two?

[Diamond]

Yes, but only for the specific reason that an intelligent agency can mimic chance and necessity. I could deliberately take a can of paint and dump it on your neighbor's patio, and the resulting blob of paint might be indistinguishable from one caused by the can of paint accidentally falling off the patio table. Though the blobs might be indistinguishable, one results by chance, the other by design.

Cordially,