The Ogri were a species of silicon-based lifeforms native to Ogros.
Biology
The Ogri looked like large rocks, usually taller than a human but irregular in shape. They were large, slow and heavy, sometimes weighing as much as three and a half tons, but they could take a lot of damage, both energy-based and physical. When awake, they would glow and make a loud rumbling noise. Like other silicon-based species, they broke down into grit when killed and also left silicon behind when they moved. (TV: The Stones of Blood)
Ogri could survive erosion. As sand, they could still attack other living beings. They could use the skeletons of their victims to give themselves structure. (COMIC: Seaside Rendezvous)
They fed on various types of proteins which were common on Ogros. When on Earth, the Ogri relied on blood globulin, which they could absorb by touch. They had long lifespans, living for thousands of years. Ogri were not shown to communicate and did not show any signs of significant intelligence, although they were seen to respond to orders. (TV: The Stones of Blood) They could be modified to give them intelligence. (PROSE: Legacy)
History
In 1826, the crew of the Camara discovered an Ogri on one of their voyages and decided to bring it back England. During the trip, the Ogri killed three of the ship's crew members. When the ship reached the Irish Sea, the crew decided to throw the Ogri overboard instead of bringing it to their home. During the process, the Ogri killed a fourth person, but the crew were successful in getting it off the ship. (COMIC: Seaside Rendezvous)
Cessair of Diplos took three Ogri from Ogros, which she used for protection and to impress the humans of Earth. These Ogri waited with the Nine Travellers until they were awoken by Cessair or her followers. In the 1970s, Cessair came into conflict with the Fourth Doctor.
During this time, one Ogri fell off a cliff, one Ogri was killed by a Megara and the last was captured by the Megara, planned to be returned to its home planet. (TV: The Stones of Blood)
At least one Ogri was discovered on Earth prior to 1983, and ended up in the care of Isaac Summerfield in Little Caldwell. It resided in the cemetery and was routinely fed blood to keep it docile. It was instrumental in saving Little Caldwell from the attention of NATO, by killing a rogue NATO commander responsible for a number of abductions (both alien and human). (PROSE: Return of the Living Dad)
In 1991, the Ogri that was dumped into the Irish Sea in 1826 began attacking people at beaches along the English coast. By this time, it had been completely eroded by the sea. It gave itself form with the skeletons of its victims. When a building caught fire in Blackpool, the Ogri was attracted to the heat. The Seventh Doctor was waiting for it with Ace. While Ace distracted it, the Doctor got the local firefighters to blast the Ogri with their hoses. After the Ogri melted into a pile of sand, the Doctor poured it into the fire where it was killed by the extreme heat. (COMIC: Seaside Rendezvous)
In 2010, UNIT had an Ogri in Underbase 1. (COMIC: The Age of Ice)
In the 30th century, Ogri had a presence in the Minerva system. In 2992, two Ogri were part of President Vargeld's entourage. (PROSE: The Fall of Yquatine)
In the 40th century, augmented Ogri were used by the Galactic Federation as doormen. (PROSE: Legacy)
Other information
In 2008 Mr Smith mentioned that the Ogri of Ogros were noted in his data base. He added that silicon-based lifeforms like the Ogri couldn't survive if they were turned into stone by a Gorgon. (WC: The Gorgon)