Thalassa replied (perhaps reluctantly) that the box was "a kind of a coffin," and that there was a dead man inside of it as well as the diamonds, but he, at all events, was not likely to run off with them.
Remington and Turold were startled by this answer, and conferred hastily apart.

They returned to ask more questions.

They wanted to know how the body and the diamonds had got there in the first instance, but that was a story which Thalassa refused to reveal.

That had nothing to do with it, he said.

The ship which had buried the man there had gone down afterwards with all hands, so nobody knew about the diamonds except him.
After that Remington became the chief questioner, Robert Turold merely looking on, his dark eyes frequently meeting Thalassa's.