The soursop is a very desirable tropical fruit, recognized as one of the new "Super Fruits" with antioxidant qualities. Its fruit is large and quite soft when fully ripe with greenish yellow spike like growths on the outside. Unfortunately usually there is not much abundance of fruit on each tree. The flesh is white and tends to have a mucous type aspect to it. Don't let that put you off because it is delicious eaten alone or used in a drink. It is like a rich dessert and one of my personal favorite fruit drinks. In a blender with ice there is practically nothing like this. ?Apparently this was the favored fruit of Christopher Columbus.
References
http://en.wikipedia.org/wiki/Annona_muricat
http://www.hort.purdue.edu/newcrop/nexus/annona_muricata_nex.html
http://www.hort.purdue.edu/newcrop/morton/soursop.html#Description