What type of rock forms from heat and pressure altering existing rocks?

Metamorphic rock

In 'Raiders of the Lost Ark', what artifact is Indiana Jones seeking? What is the hardest natural substance on Earth? In wrestling, which medal was awarded to Rulon Gardner in the 2000 Olympics when he upset Alexander Karelin? Who was the frontman of the band The Smiths? Which former MLB player served as a fighter pilot in the Korean War?