That thing on the left is an ebony coaster/tray which gets placed underneath a tasting cup/aroma cup set during a Gongfu Cha session. The thing on the right is way too full of fingerprints!
I have, cheap on more than one occasion, diagnosis seen one of those coasters in my peripheral vision and thought it was my phone. I have not ever tried to answer or make a call with one, though. I have also never placed small cups of tea on my phone.