Citrus australis

Citrus australis, the Dooja, round lime, Australian lime or Australian round lime, is a large shrub or small tree producing an edible fruit. It grows in forest margins in the Beenleigh area and northwards, in Queensland, Australia. Citrus australis is a tree up to 20 m (66 ft) tall. Fruits are spherical or slightly pear-shaped, 25–50 mm (0.98–1.97 in) across, with a thick green or yellow skin and pale green pulp. The 1889 book The Useful Native Plants of Australia records that "The fruit, which is an inch and a-half in diameter and almost globular, yields an agreeable beverage from its acid juice."...read more on Wikipedia.