Calling this stainless steel scrubber a "sponge" is a stretch, but these time-proven scrubbers worked as well in 1973 as they do today. These photos come from an eBay auction in 2/2018.

The Weber Stainless Sponge makes its first appearance in the 1973 Weber Product Catalog. In the 1974 catalog, it's listed with a retail price of 79 each. The stainless sponge is also shown in the Accessories section of a circa-1974 Weber recipe booklet shown below.