dammit....wandered by too late
Its the infamous London Hammer....a US creationist dimwit bit of cod "evidence" that creationism is fact. Whilst corrosve to sound thinking it is at least not a direct bit of vandalism of geological evidence such as the trail of dinosaur tracks in the US that a creationist ruined by hand carving mans footprints into to fake man existng with dinosaurs.
Theres a good breakdown of why the claim is clownshoes here, including the fact that (as I know from my geology eductaion) rapid concretion of calcite deposits can occur in decades:
http://paleo.cc/paluxy/hammer.htm
the owner, who is the proprietor of a laughably named evangelical christian creationist "museum", has refused to do any proper scentfic checks on the hammer which should tell you all you need to know as reguards its probable provenance.
Its a great example of makng the evidence fit the theory and US christian reality denial at all costs, and belongs alongside PT Barnums famous FeeJee Mermaid and The Shroud of Turin.
As to the earler post re the Roman cavalry helmet: In cases such as that we should have a law similar to Egypt where the state has the right to sieze such items as being of national historical importance. Sod the finders.

"Science flew men to the moon. Religion flew men into buildings."
"To sin by silence makes cowards of men."