How did Roz get on the island?

When the novel begins, a ship sinks in a bad storm off the coast of the island, leaving five crates floating on the water, each containing a robot. Four are smashed to pieces on the shore, while the fifth, containing Roz, winds up safely on shore. A gang of sea otters discovers the crate as the sun comes out. The otters and all the animals of the island are terrified of Roz, for they do not know what to make of her. They call her a monster. Roz knows nothing about herself other than she is a robot designed to do as she is told and to find better ways of doing what she does.