For Star Trek fans, April 5 is known as First Contact Day, the day of the initial meeting between humans and Vulcans. With Star Trek Beyond hitting cinemas in July, director Justin Lin took the opportunity to tweet an on-set picture. Not only does this image reveal new alien races, it seems that there might be some famous faces underneath the make-up. Check it out below:

Lin accompanied the tweet with a blog post that revealed that he had previously worked with the two mysterious alien actors. He offered the prize of crew T-shirts and posters to whoever correctly guessed their identity.

“Here I am hanging with two of my favorite people to ever work with,” he wrote. “I know this will probably be a tough one since the casting of these two actors hasn’t been announced yet and you won’t find them listed on IMDb. So here’s a hint–I’ve worked with them both before STB.”

The suggested names that followed the post included Dwayne Johnson, Vin Diesel, Kim Kold, Sung Kang, and Danny Pudi.

Star Trek Beyond is set for release on July 22, 2016. It stars Chris Pine, Zachary Quinto, Idris Elba, Karl Urban, Zoe Saldana, Simon Pegg, and John Cho, and is the third film in the series since it was rebooted in 2009.