The mystical artifact called Mithra Meteor (or Mithras meteorite) was discovered by Edward Dawson who was the first who was turned into Lion-Mane, an avatar of a suppously an alien race. Hawkman destroyed the amin stone but its fragments still could activate the transformation.
Later it was believed to be the trigger to awake the Lion avatar.
The Mithras meteorite also caused Karen Ramis go in a similar transformation.
The true origin of the meteorite is still unknown.