Jaime,
On the left are mangabas (hancornia speciosa); on top, the redish ones, are cajus (anacardium occidentale); on the right are mangostao (garcinia mangostana).
I would recommend that you visit a market in Belem, called "Mercado-Ver-O-Peso". Belem is located in the "mouth" of the Amazon river. Belem is an interesting place to visit. In Belem, there is an ice cream store that you can taste 100 ice cream flavors. The ice creams are made using fresh fruit.