A person contacted the BBC on Thursday and said he recently found the fragment on the Macaneta peninsula.
He said the pieces were "reasonably light, did not have metal on the outside, and looked extremely similar to photos posted on the internet of other pieces of debris from aeroplanes."
Don Thompson, a British engineer who is part of an informal international group investigating MH370, said the piece found by the person "does look like it's part of Boeing 777", most like a leading or trailing edge closing panel from the wing or tail.
"It's in the right area where debris is expected to wash up," he told the BBC, saying it indicated the accuracy of drift models which show how debris might have moved from the crash site.
Read More: Search for MH370 likely to end by August
The piece will now be examined by the official investigation team in Australia.
Five fragments have so far been confirmed as being definitely or probably from MH370.
MH370, flying from Kuala Lumpur to Beijing, had 239 people on board when it vanished on March 8, 2014.
It is presumed to have crashed into the southern Indian Ocean after veering off course.
Australian, Malaysian and Chinese ships have been searching 120,000 sq.km of seabed using underwater drones and sonar equipment.
More than 105,000 sq.km has been searched, but they say the mission will end by around August if there are no further significant finds.