Truss told reporters that a number stamped on the piece of debris would help to identify it.
Malaysia's deputy transport minister also said Thursday it was "almost certain" that the plane part was from a Boeing 777. It would take about two days to verify if the piece was from MH370, Abdul Aziz Kaprawi told Reuters on Thursday.
BEA, the French counterpart to the National Transportation Safety Board, said it was also studying the part. However, the agency added that it could not officially confirm yet that it was from a Boeing 777.
Local media also reported Thursday that the remains of a suitcase had also been found in the same area where the debris was recovered. Officials did not immediately comment on the reports.
The Malaysian jet was carrying 239 people when it disappeared about an hour into its journey from Kuala Lumpur, Malaysia, to Beijing, China, on March 8 last year.
Search efforts led by Australia have focused on a broad expanse of the southern Indian Ocean off Australia, roughly 2,300 miles from Reunion Island.
Professor Charitha Pattiaratchi, of the University of Western Australia Oceans Institute, told APTN that finding a piece the debris on Reunion was "entirely consistent with current patterns in the Southern Indian Ocean to be originated from the area that they're doing the current search for the wreckage."
He added: "It would not surprise me if more debris will be washing up in that part of the region in the coming weeks."
In an earlier briefing with reporters, Truss said that the development could finally provide answers for relatives of those aboard the jetliner — including Sarah Bajc, the girlfriend of missing Texan Philip Wood.
"If the wreckage is identified, what that does is give some degree of closure to the families who are waiting for information," he said. "If it can be established beyond doubt that the aircraft has gone into the water then that helps people to understand what happened."