UFOs are commonly thought of by non-scientists as alien space craft. That doesn't make them so.
Tomatoes form from the ovary of the flower; they grow on a stalk with a calyx at the base, and they're full of seeds - just like apples, plums, strawberries.
Still, it's not a big deal.
http://www.thefreedictionary.com/fruit - usage note:
fruit (fr
t)
The ripened ovary of a flowering plant that contains the seeds, sometimes fused with other parts of the plant. Fruits can be dry or fleshy. Berries, nuts, grains, pods, and drupes are fruits.
Fruits that consist of ripened ovaries alone, such as the tomato and pea pod, are called true fruits.
Fruits that consist of ripened ovaries and other parts such as the receptacle or bracts, as in the apple, are called accessory fruits or false fruits. See also aggregate fruitmultiple fruitsimple fruit, See Note at berry.
Usage To most of us, a fruit is a plant part that is eaten as a dessert or snack because it is sweet, but to a botanist a fruit is a mature ovary of a plant, and as such it may or may not taste sweet. All species of flowering plants produce fruits that contain seeds. A peach, for example, contains a pit that can grow into a new peach tree, while the seeds known as peas can grow into another pea vine. To a botanist, apples, peaches, peppers, tomatoes, pea pods, cucumbers, and winged maple seeds are all fruits. A vegetable is simply part of a plant that is grown primarily for food. Thus, the leaf of spinach, the root of a carrot, the flower of broccoli, and the stalk of celery are all vegetables. In everyday, nonscientific speech we make the distinction between sweet plant parts (fruits) and nonsweet plant parts (vegetables). This is why we speak of peppers and cucumbers and squash
all fruits in the eyes of a botanist
as vegetables."