Awww I'm so sorry to hear about Mars. The loss of any pet is always hard to deal with especially with children. It is though a life lesson to learn and up to us parents to help them accept the loss and cherish the memories. I've faced it with my own kids and various pets over the years. It's never easy but it is a part of pet keeping all parents have to face with their kiddo's. Big hugs and sorry to hear about little Mars passing today.