He had come to find out things.
What was it that this shell rested upon?
Seizing two of the ribs with a strong clutch, he let himself hang over the sides of the shell until his feet were level with its lower side.

They touched something hard.
He pressed them downward; it was very hard.

He raised himself and stood upon the substance which supported the shell.

It was as solid as any rock.

He looked down and saw his shadow stretching far beneath him.