It might come as a surprise, but your smartphone is covered in germs and these bacteria photography shots help show just what's living on a phone. A project completed by students at the University of Surrey, the set of photographs were created by placing various smartphones onto a plate that allows for growth and then documenting the resulting growth.
There is natural bacteria living on everything and everyone, so there's no point in getting too grossed out, but this set of bacteria photography helps solidify that it might be time to clean your phone. It's no surprise because we take our phones with us everywhere and touch them dozens of times a day.
Bacteria on a mobile phone can be kept to a minimum by making sure to clean the device regularly using a little bit of alcohol and a soft sham; this will limit growth and might even protect from illnesses you might have collected on the phone.