In the second paragraph, the appending detail about the butler's thumb could be most accurately described as?

Question from second paragraph of chapter 3. Paragraph 2: "Every Friday five crates of oranges and lemons arrived from a fruiterer in New York--every Monday these same oranges and lemons left his back door in a pyramid of pulpless halves. There was a machine in the kitchen which could extract the juice of two hundred oranges in half an hour if a little button was pressed two hundred times by a butler's thumb."

In the second paragraph, the appending detail about the butler's thumb could be most accurately described as...

anomalous? hyperbolic? superfluous? ironic? or enigmatic?