Michael Lopez is Google's lead web designer. He is part of the team that creates the Google doodles.
They celebrate birthdays like Frank Lloyd Wright's; moments in history like the landing of the Mars rover or holidays like Valentine's Day.
"When we have an idea, a great concept, as long as it's with it's something relative to Google and the technology and the culture," Lopez said.
The celebration of the discovery of DNA elicited calls from geneticists who said the colors were wrong.
"So we had to make a quick color tweak," Lopez said.
The Google doodles started more than 10 years ago when Google founders Larry Page and Sergey Brin took off for the Burning Man festival.
"It was kind of an out-of-office message for our users so Sergey put up a Burning Man logo on our home page," Lopez said.
That was 1998. Now there have been more than 500 Google doodles.
It really is the world's largest art gallery. Doodles on the Google home page have been seen by billions of people.
So how does it work?
"We start with sketches, writing on paper, napkins, on the walls, the office, everywhere," Lopez said.