Despite the announcement of the PlayStation 4, Naughty Dog is still putting the finishing touches on what is likely to be one of the last big exclusives for the PlayStation 4.

The Last of Us is now a little over three months away from its delayed June 14 release date, and but the game’s marketing campaign is rolling ahead with developer diaries that give gamers a glimpse into what the developers were thinking while designing and implementing the game. First on the list of things they were thinking: the “zombies” aren’t zombies.

In the first The Last of Us dev diary, titled “Hush,” Naughty dog talks about its inspirations for the “infected,” including parasitic fungi that take over ants. The art design for the infected evidently came from research done on real skin infections and fungal infections, which explains their disgusting appearance. The developers go on to comment about the sound design for the infected and a bit about their life cycle.