Dry tears 3
Very likely "shimmers" is not a noun in a separate line, as in "And the shimmers as flies scoop up meat", for a specific reason: the verb makes a more fluent and logical line. But we can refer to the shimmers from the carcass as a noun for practical reasons: it highlights one of the only two words related to an opal stone: "pebble" and "shimmers". The shimmers, whatever they represent, can be seen in an opal, and the carcass can be seen as their bare background, illustrated in the winding patterns of the opal. Syd likes gems, and could be staring at it long enough to be inspired to write a song:
Syd was sitting there at the table, and the box of cereal was between us. And he was watching the box of cereal the way that I would watch 'Star Trek' on television. He was seeing something I wasn't seeing. I don't know what he was on, but he could have sat there all day, staring into that cereal, and he would have been just as happy as anybody else.