Question: Has a tumulus been discovered on Mars?, Answer:No, Description of Tumulus: Mound of earth and stones raised over graves, Fact1: A tumulus is a mound of earth and stones raised over a grave or graves., Fact2: A grave is a location where a dead body (typically that of a human, although sometimes that of an animal) is buried., Fact3: Mars has only been explored by unmanned spacecraft., Fact4: Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there remains unknown. 
Step1: What do tumulus cover?, Step2: What do #1 contain?, Step3: What is a previous condition for something to be considered now #2?, Step4: Have things with the characteristic of #3 been to Mars?, Wikipedia page for step 1: Tumulus, Wikipedia page for step 2: Graves (burials), Wikipedia page for step 3: Death, Wikipedia page for step 4: , not_definitive_answer: False, incorrect_answer: False