World publishing rights (excluding North America) for Spin Master’s hit toy property Hatchimals have been acquired by Penguin Random House Children’s UK.

Spanning three years, the publishing program will build the Hatchimals world with fiction, activity formats and a collector’s guide. The first fiction title (The Giggling Tree) and the first sticker activity book (Magical Adventures) will launch in the UK in May.

The rights were acquired by Penguin Random House Children’s UK editor Beth O’Leary and head of acquisitions Rich Haines. Penguin Random House Children’s US will also partner with Spin Master on a range of upcoming titles for the North American market.

The Hatchimals toys—eggs that hatch to reveal their inner colorful creatures—debuted in October 2016 and became the hit toy of the holiday season. Following the brand’s launch, Spin Master’s Q3 revenue rose 23% to US$475 million.

Spin Master is set to expand the Hatchimals line in 2017.