How do hard seeds of many Sapindales plants survive being eaten by birds and mammals?

Many plants within the order Sapindales produce fleshy fruits that are highly attractive to birds and mammals, facilitating a process known as endozoochory.12

These plants have evolved to ensure their survival through this mutualistic relationship. While the fleshy parts of the fruit or the aril surrounding the seed provide a nutritional reward to attract these animals, the seeds themselves are protected by a hard, durable structure. Because these seeds are resistant to digestion, they are able to pass through the animal's alimentary canal completely intact.132

By remaining unharmed during the digestive process, the seeds are eventually excreted by the animal, often at a distance from the parent plant, which aids in effective seed dispersal. This strategy relies on the seeds remaining viable throughout the journey, distinguishing this beneficial dispersal mechanism from seed predation, where the seeds would be destroyed by digestion.2