 Who are the animals that Purnie plays with?
When Purnie had stopped time, the bees—like all the other creatures he met—had been arrested in their native activities, and he knew that as soon as he resumed time, everything would pick up where it had left off. Further down the beach was a pair of two-legged animals poised in mid-step, facing the spot where Purnie now stood. He scampered around the rockpile and down the sandy cliff to meet the tripons who, to him, had just come to life. The tripon thought Purnie's feat was superb. Purnie ran from pillar to post, trying to see and do everything at once. Purnie shrieked with joy at this new frolic and promptly stood on his head.
 They are humans.
 They are three-legged ostriches.  They are a flock of spora.  They are mannikins.  They are humans.