The "Smiling Dolphin" meme which went viral on X, is based on a photo of the Yangtze Finless Porpoise named Miharu, first uploaded to the internet on ZooChat in 2023.
It gained popularity, becoming a reaction meme after the image of Miharu resurfaced and users started using it as a meme.
Miharu can be found at Miyajima Public Aquarium in Japan.