Pictures of giant grapes, larger than the average chicken egg, have been doing the rounds on Vietnamese social media this week, raising questions about their authenticity and origin.

Novelty fruits are particularly popular in Japan, where specialized shops can sell certain varieties of apples, peaches, melons or grapes for mind-boggling prices. However, the popularity of such fruits has spread throughout Asia, and recently the Vietnamese owner of a market stall shared some photos of a new variety of grapes imported from Japan.

Using social media to promote new products is fairly standard these days, only these photos got a lot more attention than usual, because of the apparent size of the grapes. Some of these white grapes seemed to be larger than a chicken egg.

Vietnamese website VietnameNet was among the first outlets to feature photos of the giant grapes, claiming that they were a new Japanese “vip variety” sold at a whopping 7 million dong ($300) per bunch. That’s very expensive, even for novelty fruits; Japanese pione grapes, for example, are sold for around 2.5 million dong ($107) a bunch.

Like all Japanese novelty fruits, these grapes aren’t sold by weight, but by bunch, with each bunch having to abide by very strict quality standards. For example, these ultra-rare grapes have to weigh at least 1kg per bunch, and each grape must be between 4 and 5 cm in diameter in order qualify for commercialization and export.

Ms. Khuc Ngoc Anh, the owner of a high-end fruit shop in Xuan La, Hanoi, was the one who posted the photos of the vip grapes when they arrived from Japan. She was trying to get people interested, so she used an actual chicken egg to show just how huge the grapes were. The technique worked, and in just a few minutes all the 50 bunches she had ordered were sold.

The shop owner said that the grapes are a very new variety of white pione grapes from the Japanese province of Nagano. The first shipment and the photos she posted generated overwhelming interest from customers, but she told VietnamNet that she is struggling to secure a new shipment, because of how rare the new variety is.

Interestingly, the giant grapes are not as expensive as the more famous Japanese Ruby grapes, which can sell for as high as 11 million dong ($475) per bunch. They are known as the world’s most expensive grape variety, with the most expensive bunch ever selling for a whopping 1.1 million yen ($11,000), back in 2016.