bouncer

The stone must be a bouncer.

"… when he wants to accomplish his purpose, he does not hesitate to invent—I am not quite sure of the word, but I think it is “bouncers.”

"Why, I'll tell you, Mr. Simple; he's a good tempered, kind fellow enough, but—" / "But what?" / "Such a bouncer!!" / "How do you mean? He's not a very stout man." / "Bless you, Mr. Simple, why don't you understand English. I mean that he's the greatest liar that ever walked a deck.[…]"

He shook his head and took up the child—Dilly kicked out her feet in tiny electric jolts to the full stretch of the Babygro.[…]He put the child in the bouncer again.