Indiginous to Ecuador, this natural papaya hybrid is torpedo shaped and has five flattened facets. When sliced crosswise, the facets give this exotic fruit a pentagonal outline. Babacos range from 8 to 12 inches long and are about 4 inches in diameter. The skin, which is entirely edible, turns from green to golden yellow as it ripens. The riper and softer the fruit, the more flavorful it is. The rich flavor of the extremely fragrant babaco is a cross between banana and pineapple, though not as sweet as either. The juicy, creamy white flesh has a texture similar to that of a casaba melon. The hard-to-find babaco is sometimes available in specialty produce markets. It will ripen quickly at room temperature, especially if placed in a brown paper bag. Refrigerate ripe fruit and use as soon as possible. Babaco is best eaten raw. It contains triple the amount of papain as the papaya and is a good source of vitamins A and C.