A thick tree grows from a book of poems laying on its side, forming an intriguing piece of art. The sculpture is titled “Poetree,” and it was the first of 10 sculptures made from the pages of books to be secretly donated to a number of libraries and other cultural places of interest in Edinburgh, Scotland.

“Poetree” mysteriously showed up at the Scottish Poetry Library in 2011 accompanied by a note saying, “in support of books, libraries, words, ideas.” It was gifted as a response to the cutbacks and closures affecting libraries, and was later joined by two other sculptures, one of a cap and gloves and another of a girl reading beneath a tree.

Between March and November 2011, the 10 original book sculptures appeared at cultural institutions throughout the city. An 11th sculpture was gifted to author Ian Rankin. Like the first 10 works of art it, too, was created from old books.

The original book sculptures garnered national and international attention. They even went on a tour around Scotland in 2012, though they soon returned to their Edinburgh homes.

Though more book sculptures have popped up in the years since the originals first appeared, to this day, the sculptor remains anonymous. All that’s known is that the mastermind behind the mysterious works of art is a woman.