week-to-week graph compared to the Steelers. What the two teams have in common is that they are playing their best football right now. The Giants have had their four best single-game DVOA ratings of the year over the last five weeks. The Steelers have had three of their top five games of the season over the last four weeks.

Nearly every team between the Steelers at No. 3 and the Giants at No. 11 saw its DVOA rating drop a little bit this week. Those kings of close losses, the Philadelphia Eagles, went back up a spot to fifth, but only because Kansas City's rating fell more than Philadelphia's. (You can read more about Kansas City's fall and running game problems in this week's Any Given Sunday.) The EaglesThe echinoids are encased by a rounded skeleton called a test. Their bodies have an enormous number of sharp spines protruding in all directions, providing protection from potential predators. The spines attach to the body with a ball-and-socket like attachment, which can also aid in movement.

Echinoids have five paired rows of podia (structures somewhat like a foot) which, when extended, are long enough to reach beyond their spines. Their mouth (containing five teeth that are pointed towards the centre) is located on the underside of the animal.

Herbivorous urchins use their podia to pull themselves against the ocean floor and gnaw at algae with their mouth.

Echinoids are also a model animal in developmental biology and were the first organism used to prove that sperm fertilised the ovum.