Costasiella kuroshimae

Costasiella kuroshimae—also known as a "leaf slug", or "leaf sheep" —is a species of sacoglossan sea slug. Costasiella kuroshimae are shell-less marine opisthobranch gastropod mollusks in the family Costasiellidae. Despite being animals they indirectly perform photosynthesis, via kleptoplasty.

Description
Discovered in 1993 off the coast of the Japanese island Kuroshima, Costasiella kuroshimae have been found in the waters near Japan, the Philippines, and Indonesia. They live in tropical climates. They have two dark eyes and two rhinophores that emerge from the tops of their heads that look not unlike sheep's ears or insect antennae, hence the common name "leaf sheep". They range in size from 5 to 10 mm in length.

Costasiella kuroshimae are capable of a physiological process called kleptoplasty, in which they retain the chloroplasts from the algae they feed on. Absorbing the chloroplasts from algae then enables them to indirectly perform photosynthesis.

The type locality is Kuroshima, Taketomi, Okinawa, Ryukyu Islands.