Finger Limes are getting to be popular. Stop by the farm if you want to try them. People call them "lime caviar" because inside the green/black/pink skin are hundreds of crisp tiny sour vesicles of juicy goodness. The flowers are pink/white and tiny and the leaves are much smaller than other citrus trees have.
It is naturally found in Australia and is very popular with chefs who like it as an attractive garnish for hors d'oeuvres, seafoods esp sushi or added to a salad or a salad dressing for a tangy pop when you bite them.
They are an understory tree or bush and so hot full sun may be too much for them. They need protection from frost so we cover them on the cold nights or they can be placed in a frost free section of your yard with some sun or near the house to benefit from the warmth at night. This is a fun fruit to try.