Challenges are competitions that consist of endurance, problem solving, teamwork, dexterity, and/or will power, and usually are designed to fit the theme of the current season. A common style of challenge is a race through a series of obstacles to collect puzzle pieces which then must be assembled once all pieces have been collected. Challenges have also included "gross food" challenges (including clean, edible fauna that populates the locale), and knowledge quizzes. Many seasons also include during individual challenges: a 'loved one' challenge where a family member, friend or significant other of each player participates or is part of the challenge reward; the 'Survivor Auction' in which contestants bid against each other on luxury items and strategic advantages; a challenge in which the winning contestant receives a car; and a challenge that includes components of previous challenges in that season, known as 'Second Chances'. Some challenges have had the teams competing at their own beaches by constructing a shelter or an SOS signal, the results then judged by an expert; teams are only told if they win if they receive a package dropped from a plane or by delivery of the victory spoils by boat.