Russian scientists believe they have recovered fragments of a meteor that exploded spectacularly near the Ural Mountains.
The tiny samples were found near a frozen lake in Chebarkul, where an eight-metre crater has formed in the ice.
Initial searches of the lake failed to find any traces, but a scientific expedition on Sunday recovered unusual rocks nearby, which appear to match the composition of meteorites.
Viktor Grokhovsky, a member of the Russian Academy of Sciences , told the RIA Novosti news agency: "We confirm that the particles of a substance found by our expedition near Lake Chebarkul really do have the composition of a meteorite."
Mr Grokhovsky's Urals Federal University posted a photograph on its website of a person holding a tiny piece of porous black rock between his index finger and thumb.
"This meteorite belongs to the class of regular chondrites," a university statement said.
"Most likely, the find will be called Meteorite Chebarkul."
More than 1,200 people were injured on Friday, mostly by broken glass and damaged buildings caused by a pressure wave accompanying the meteor blast. It caused an estimated £21m worth of damage
The meteor fragmented between 20 and 30 miles above the Earth's surface and may have scattered pieces over a large area of the industrial region.
Meteor rock that survives the journey through the Earth's atmosphere to reach the ground is known as meteorite.
Mr Grokhovsky said the fragments were approximately 10% metallic iron, combined with substances called chrysolite and sulphite.
Russian authorities have set up a cordon around the lake to deter meteorite-hunters and independent researchers, but Grokhovsky said he was confident their findings indicated a much larger meteorite was concealed within the lake.
He said they had found around 50 tiny fragments from the snow close to the lake.
"The lake is still cordoned off, but it is quite clear that a meteorite is buried there," he told the Interfax news agency.
"Since we found the fragments - traces of the upper layers of the meteorite - that means that its main mass is resting in the lake."
Mr Grokhovsky explained that his research team was not acting on the authority of the Russian government, but that he had felt compelled to take action because it was such a rare and scientifically important event.
"We decided to do this on our own," he said.
"As a member of the Russian Academy of Sciences committee, I simply could not stand idly by. So I decided to send our guys there."
Other meteorite-hunters may be less altruistically-motivated. Adverts have been posted on Russian websites offering as much as 300,000 rubles (£6,400) for an authentic piece of the Chebarkul meteorite.