Science news this week: ‘Spiderwebs’ on Mars, tigers’ return to Kazakhstan, and 2,000-year-old skull with permanently blackened teeth Live ScienceGiant ‘spiderwebs’ on Mars contain tiny egg-like structures that scientists ‘can’t quite explain,’ new photos reveal YahooNASA rover spots bizarre landscape on Mars MSNNASA’s Curiosity Rover Sees Martian ‘Spiderwebs’ Up Close NASA (.gov)Curiosity Blog, Sols 4812-4819: Back Into the Hollows NASA Science (.gov)