Of interest, is the debris item just NW of the Last Known Position and marked "07". I have no information as to what it is, but it was found on 7 June 2009 and I suspect that it has broken loose from the bottom. It could have just surfaced, but there is no way of telling when.
Considering the reported depths, I think that it is doubtful that anything that made it to the bottom would have any flotation left. The squeeze pressures would flatten every air pore.