April Fools Day is fast on its way to becoming an international day of celebration for fans of Bill Watterson's seminal comic strip Calvin and Hobbes. Fellow cartoonist Berke Breathed's Bloom County revival has brought with it the added bonus of what appear to be new Calvin and Hobbes strips that were apparently created in collaboration with Watterson.Today, a new "Calvin County" comic, signed by both Watterson and Breathed debuted on on the Bloom County , and it marks the welcome return of Spaceman Spiff, Calvin's space hero alter-ego and follows him as he has adventures on a strangely-familiar asteroid.RELATED: Berkeley Breathed's 'Calvin and Hobbes' gag wins April Fools' Day

This follows Calvin's April 1st, 2018 appearance in "Calvin County," where he finds himself in a very characteristic time travel dilemma.

The first mention of Watterson on the Bloom County site occurred April 1st, 2016, Breathed offering a joking update on Watterson's alleged health, that he was "continent and looking forward to some well-earned financial security." The jest appeared to have coaxed Watterson from his retirement, if only briefly, and a black and white strip featuring Watterson's pair as zombies followed.

The strips appear with no commentary from either artist, which is not a surprise from the infamously private Watterson. However, it's a bit more surprising from the usually voluble Breathed.

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Watterson is known not only for his brilliant comic work, but also for the strict control he maintains over it. He has never authorized Calvin and Hobbes merchandise, nor has he licensed the characters for film or television. The strip ran from 1985 - 1995 and has continued to maintain an appeal that has crossed generations of readers, long after its natural conclusion.

After ending in 1989, Breathed's Bloom County was revived in 2015 and still appears regularly on the the artist's Facebook page and other social media outlets.