Heard spent the day with Musk’s five sons while sightseeing in Australia over the weekend. The actress shared a few snaps from their day out, showing the group goofing off together at the Sydney Opera House.
In one photo, Heard, 31, is seen enjoying a piggyback ride from one of Musk’s sons, while in another snap, three of the kids pile on their father.
“Kidding around,” the actress captioned her post.
Musk’s sons — Damian, Kai, Saxon, Xavier, Griffin — are from his marriage to his first wife, Justine. (The couple had another son, Nevada, who died at 10 weeks.)
The billionaire tech mogul, 45, also shared photos from the day on his own Instagram account. In one snap, Musk is seen with his arm around Heard as one of his sons shows the couple something on his phone.
“Sydney is such a beautiful city,” he wrote.
And this isn’t the first time Heard has spent time with Musk’s kids. The group enjoyed a day of adventure at the Gold Coast’s Currumbin Wildlife Sanctuary in April, taking part in the TreeTop Challenge ziplining ropes courses.
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Dating rumors began swirling last year when Heard and Musk were spotted out together several times amid their respective divorces — Heard’s contentious divorce from Johnny Depp was finalized in January, and Musk filed for divorce from his second wife (and Westworld actress) Talulah Riley in January 2015.
“Elon and Amber are already very serious about each other,” a source told PEOPLE earlier this month. “She spends a lot of time at his house and is very comfortable there. Amber’s also gotten to know his kids and spends time with them as well.”