We didn't think that 115th anniversaries were all that important. But over at Mountain View they must be, as Google's latest Doodle celebrates that very anniversary for the discovery of X-rays.

Wilhelm Röntgen was the first chap to study the effects of X-rays after coming across them on 8 November 1895 while he was experimenting with Crookes tubes. For his troubles he was awarded the first ever Nobel Prize in Physics, 16 years later.

However, like an X-ray you have to take a closer look at the Doodle to get a real-feel for what's going on underneath the surface.

Google's vice president of geographic and local services Marissa Mayer tweeted saying: "115th anniversary of the X-Ray on Google (with a shoutout to April Fools 2002 - PigeonRank - in the little 'g').

Sure enough, take a look at the little g and you'll see the bones of a pigeon.

If you're unfamiliar with PigeonRank, it was a prank Google pulled, which stated that the search engine was powered by a band of super intelligent pigeons who could select the most relevant websites.

If anyone knows the significance of the key in the first o, or the rubber duck in the second one, then give us a shout.

If you like Google Doodles then check out Google's birthday Doodles - the pictures that got them to 12

And Google Doodles that are out of this world