Dillenia indica (calta)

Dillenia indica produces a large hard edible[3] fruit which is accessible only to the megaherbivores in the wild. A study in the Buxa Tiger Reserve by ecologists Sekar & Sukumar has shown that Asian elephants appear to have a particular fondness for the fruits of D. indica, and are hence an important seed disperser for this tree. With the prospect of extinction of the elephants this tree has developed a back-up system, whereby its hard fruits that were only accessible to megaherbivores, slowly soften on the forest floor through the dry season to allow access to successively smaller animals such as macaques, rodents and squirrels. Seeds from both old and soft fruits are able to germinate well, enabling the persistence of this tree to be independent of the survival of its major megaherbivore disperser.[6]
wikipedia
photo credit amazon