From Blaseball Wiki

After a mascotless season 4, fans thought that the age of ever-changing line-up of mascots were over. This all changed when during the run up for season 5 the Canada Moist Talkers twitter account and announced the existence of H O R K .

"Found in Eugenia Garbage's favorite trash can, a lovable mound of what looks to be a slime mold with three googly eyes on it was found by one of our stadium employees this morning. This card was also attached."[1]

Major Theories

Many fans wonder where the H O R K came form. One theory suggests that after the mascotless season 4, the season 3 mascot the Moist Owlette was aimless and felt loss and sought refuge in it's only friend Eugenia Garbage. Garbage let Owlette rest and play among her precious garbage and promptly forgot about her as the Canada Moist Talkers rallied to make the playoffs in Season 4.

Nobody has seen the Moist Owlette since Garbage left them to play in her garbage so many suspect that the H O R K is actually just The Moist Owlette once it decomposed and fungus set in. Despite this almost accepted lore, the fans still show much greater appreciation and affinity to H O R K than they ever did the Owlette.