Samsung unveiled its new S7 and S7 Edge phones in a virtual reality-heavy presentation that also included the launch of 360 degree camera, the Gear 360.

But the announcements took second place to a surprise appearance by Fackbook founder Mark Zuckerberg, who took to the stage to explain why Facebook and its VR company Oculus was backing Samsung.

“VR is the next platform,” he said, adding that the current trend for using the technology for gaming and entertainment was already changing. “That’s why Facebook is investing early on,” he said.

Samsung has dabbled in virtual reality for some time, releasing the consumer version of its Gear VR headset late last year.

But Samsung is facing competition from fellow mobile phone firms HTC, which has developed the Vive system in collaboration with Valve, and LG, which showed off its virtual reality headset earlier on Sunday.

Although Samsung has worked with Oculus on the headset, it still requires a smartphone – the S6, S6 Edge, Note 4 or S6 Edge Plus – to work.

Galaxy S7

The Gear 360 will allow consumers to create their own content, sharing its with friends and family.

Samsung had been widely expected to debut the Galaxy S7 at the Unpacked event in Barcelona, with some details leaking in recent days.

Samsung’s DJ Koh described the phones as the most advanced and beautiful phones on the planet. The new Galaxy handsets have been made more powerful, and bring back some of the features removed from its predecessor, including the MicroSD card slot to expand memory and the water resistant IP68 rating.

Mobile World Congress has become a key smartphone event in the technology calendar, with hundreds of accessories shown off for the first time alongside the new devices, as well as future technologies also being broadly discussed.

This year is also expected to see discussion on 5G internet – the next generation of wireless data for phones which will bring faster internet speeds to mobile devices – which could arrive by 2017.

The congress officially opens on February 22nd and runs until February

(Additional reporting Reuters)