The outer stainless steel sphere (in the center of the image) contains a smaller inner sphere (or core) made of copper. (sciencedaily.com)
I walk over to it and sure enough, it's there, a small, steel sphere embedded in the plaster, at the height of my waist. (hyperallergic.com)
Thirteen - hundred 1,300 stainless steel spheres float on the pond at the Glass House as part of Yayoi Kusama's «Narcissus Garden,» on view through Nov. 30. (nytimes.com)