What is this upside down floating heart symbolizing? In the Nichijou short 8, Yuuko Aioi goes fishing.
After fishing up a boot and kettle, she leaves and this upside down heart shape on a leave floats by.



Supposedly this is a symbolism of sorts, hence what is this symbolizing?
It's a peach. As Aki Tanaka commented, this is a reference to the story of Momotaro, in which an old woman finds a peach floating down a river. When she and her husband attempt to eat it, they find a boy inside.