For Prince William it was the buzzy bee, for his son Prince George the Mary-Lou doll.
When a much younger William visited New Zealand with his parents in 1983 there was great moment when he played with the iconic buzzy bee on the lawn of Government House.
His son was keen on a toy today too, it just happened to be in Eden Alve's hands.
George wanted to interact with the other babies from the start, reaching for fellow baby Lily Gray while she was being held in her mother Alana's arms.
His royal prerogative shone through, however, when he took a shine to a Mary-Lou doll in possession of young Eden. He reached for the doll, and snatched it from Eden, before throwing it to the floor.
His mum Catherine, Duchess of Cambridge, smiled as she picked it up.
Happy chatter and gurgles filled the room as babies crawled between the legs of their parents, the royals and Governor-General Sir Jerry Mateparae.
Occasional wails broke out but on the whole the babies behaved admirably on an occasion which will be retold to them their whole lives.
At 3.30pm all 11 sets of parents sat in a circle on the thick carpet, the babies getting stuck into their toys while the parents talked.
The young prince's mum was dressed in a knee-length black and white patterned dress, with black high-heel shoes.
Prince William chatted easily with parents, dressed in a blue shirt, dark blue jeans, a brown and white patterned belt and brown loafers.
Kate's knee-length Tory Burch dress was chosen for its black and white colour theme, New Zealand colours, a royal press secretary said.
At 4pm the royal family left the engagement, leaving the other parents to exchange their views on the most remarkable play date their children are likely to go on.
Grant and Magda Collinge, whose baby Lukas played with George, said the royal couple were enjoying New Zealand "except for the weather".
George was a big baby and was not afraid to get stuck in and take charge, Grant said. At the beginning of the playdate George crawled straight to the middle of the toy pile, and took a particular shine to a drum toy, he said.
Porirua early childhood teacher Shiela Tagulimae said the prince was advanced for his age - the prince was hauling himself up to standing against objects while her own son, TagiiLima, was not yet ready to stand.
George was a lot more bold than TagiiLima, known as TJ, Shiela said. TJ was unsettled and a bit weepy, and kept himself to the outside of the circle, she said.
- The Dominion Post