What do tumulus cover? What do #1 contain? What is a previous condition for something to be considered now #2? Have things with the characteristic of #3 been to Mars?
Tumulus
A tumulus is a mound of earth and stones raised over a grave or graves. A grave is a location where a dead body (typically that of a human, although sometimes that of an animal) is buried. Mars has only been explored by unmanned spacecraft. Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there remains unknown. 
Mound of earth and stones raised over graves
Has a tumulus been discovered on Mars?