Google Doodles are typically used to celebrate special days such as the start of the Winter Paralympics or Pi Day, but the latest Doodle for St. Patrick’s Day does more than display something green.

The art for today’s Doodle comes from Irish artist Ross Stewart, and it shows a stonemason working hard as a sheep looks on. Several stones in the drawing form the word “google,” but when looking closer at the letter “l,” a dozen straight lines intersecting with each other can be seen. These lines represent an ancient Irish alphabet known as Ogham.

Ogham dates back to approximately the 4th century in Ireland. Horizontal, vertical, and diagonal lines represent different letters. Words go left to right and then bottom to top. With the use of an Ogham Transliterator, a person can enter a word to see how it will look. It can also be used to help decipher the markings in today’s Doodle. (Spoiler: It spells “google.”)

Ogham Alphabet
Ogham Alpahbet

Celts used the script to write Primitive Irish, an early form of Gaelic. Stone monuments have been found across Ireland with the Ogham markings. Most of these inscriptions include names of individuals such as a property owner or someone being commemorated.

It’s easy to view St. Patrick’s Day as a time when drinking green beer or pinching someone for not wearing green are seen as rites of passage, but Google decided to reflect on Ireland’s linguistic history on a day to celebrate Irish culture.