Titanic sub: What debris has been found and what does it mean?

The US Coast Guard has announced that a tract of debris has been recovered connected the seabed adjacent the wreck of the Titanic, wherever hunt teams are looking for a missing submersible.

According to dive adept David Mearns, the debris includes "a landing framework and a rear screen from the submersible".

The BBC's subject correspondent, Jonathan Amos leads america done what these uncovering suggest.