what is the role of the metal in biology?
Nickel enzymes such as urease are considered virulence factors in some organisms.
Nickel
Nickel enzymes such as urease are considered virulence factors in some organisms. 
what is shield nickel? It was the first United States five-cent piece to be made out of copper-nickel, the same alloy of which American nickels are struck today.
wiki:25682496
Nickel [SEP] Biological role
Although it was not recognized until the 1970s, nickel is known to play an important role in the biology of some plants, eubacteria, archaebacteria, and fungi. Nickel enzymes such as urease are considered virulence factors in some organisms. Urease catalyzes the hydrolysis of urea to form ammonia and carbamate. The NiFe hydrogenases can catalyze the oxidation of to form protons and electrons, and can also catalyze the reverse reaction, the reduction of protons to form hydrogen gas. A nickel-tetrapyrrole coenzyme, cofactor F430, is present in methyl coenzyme M reductase, which can catalyze the formation of methane, or the reverse reaction, in methanogenic archaea (in +1 oxidation state).