"Oh no," said the Psammead, "that would never have done. Why, of course
at sunset what was left over turned into stone. You find the stone bones
of the Megatherium and things all over the place even now, they tell
me."

"Who tell you?" asked Cyril; but the Sand-fairy frowned and began to dig
very fast with its furry hands.

"Oh, don't go!" they all cried; "tell us more about when it was
Megatheriums for breakfast! Was the world like this then?"

It stopped digging.

"Not a bit," it said; "it was nearly all sand where I lived, and coal
grew on trees, and the periwinkles were as big as tea-trays--you find
them now; they're turned into stone. We Sand-fairies used to live on the
seashore, and the children used to come with their little flint-spades
and flint-pails and make castles for us to live in. That's thousands of
years ago, but I hear that children still build castles on the sand.
It's difficult to break yourself of a habit."

"But why did you stop living in the castles?" asked Robert.

"It's a sad story," said the Psammead gloomily. "It was because they
_would_ build moats to the castles, and the nasty wet bubbling sea used
to come in, and of course as soon as a Sand-fairy got wet it caught
cold, and generally died. And so there got to be fewer and fewer, and,
whenever you found a fairy and had a wish, you used to wish for a
Megatherium, and eat twice as much as you wanted, because it might be