Thanks for asking, Mopar.
Simply stated...
The manhole cover, as a canvas, represents the intersection of technological advances, old (2500 BCE) and new (2008-2009).
The freshly spitted-out gum wad represents our recent rejection of old, stale, flavorless — arguably quite overly-chewed at this point — fiat currency.
The discarded [bitcoin] coin represents the inevitable acceptance of cryptocurrency in the near future. Within our lifetime, cryptocurrency will be so commonplace that we will hardly give its existence a second thought, much like a simple “penny” dropped on the street.
The lost bitcoin ATM receipt, which records conversion from USD to BTC (and vice versa), is there to illustrate the current point in cryptocurrency’s timeline — the point somewhere between the old fiat of the past (gum wad) and the inevitable future of bitcoin / cryptocurrency (penny). Plus, it acts as an actual receipt of funding for the art piece and acts as a sort of COA.
And the yellow line? Streets have yellow lines.
Chris@TBPCo.