As Ornithologist is a specialist of Birds similarly Archaeologist is a specialist of Archaeology.

As cat has Paw similarly Horse has Hoof.

As Water of a River flows similarly water of Pool is Stagnant.

Cup is used to drink something with the help of lips. Similarly birds collects grass with the help of beak to make her nest.

The elements move in the sequence the elements reaching the upper-left and the lower-right positions rotate 90^oACW; the elements reaching the upper-right and lower-left positions rotate 90^oCW; the central element rotates 90^oACW and gets laterally inverted.