You can find it in local markets, or see it bend the branches of the plant on which it matures, the Annona muricata.
It may seem difficult to you with its spines and huge (a single fruit can reach 2 kg of weight), but it is not only edible, but is one of the most beneficial fruits found in nature. 
We are talking about graviola, also known as Corossole or Guanàbana, very common in the equator. 
Its bright green skin (becomes a little darker and darker when ripe) is thin and has non-hazardous spines. 
The flesh is soft, generally white in colour and has a fleshy, juicy texture and a slightly acidic but very sweet taste, the fruit contains numerous black seeds which are easily removed.
It can be cut in half and tasted directly with a teaspoon, or used for the preparation of shakes.
In Kenya, where it abounds, they call it "dawa tamu", meaning "sweet medicine". 
Graviola is a low calorie fruit, rich in B and C vitamins, iron, magnesium, potassium, proteins and amino acids. 
In addition to these, there are other elements with particularly therapeutic indications: acetogenins with anticancer qualities, Y-aminobutyric acid (GABA) for anxiety, coumarins against bacteria and much more. Precisely for these qualities, the fruit - but also the plant and the leaves, where these elements are most evident - has been used for centuries as a natural remedy for the treatment of the most common pathologies, from infections to high blood pressure (the intake of the fruit leads to a natural drop in blood pressure, therefore the use can be indicated for those who suffer from hypertension).
Graviola intake is also recommended for the treatment of intestinal worms, in case of stress and nervous problems, to eliminate lice, as well as to tone and strengthen the heart.