Tove Jansson said this quote

Then -- they saw the Groke. Everybody saw her. She sat motionless on the sandy path at the bottom of the steps and stared at them with round, expressionless eyes.She was not particularly big and didn't look dangerous either, but your let that she was terribly evil and would wait for ever. And that was awful.Nobody plucked up enough courage to attack. She sat there for a while, and then slid away into the darkness. But where she had been sitting the ground was frozen!