Answer: A Tortoise

In September 1968, Zond 5, an unmanned version of the Soyuz 7K-L1 lunar-flyby spacecraft was carried aloft by a Proton-K/D rocket; it became the first spacecraft to travel to the moon, circle it, and return safely back to Earth. In addition to performing this space exploration feat successfully, it also marked the first time an animal had ventured that far into space and returned safely.

Aboard Zond 5 were a pair of Russian tortoises along with fruit fly eggs, cells of wheat, barley, peas, pine, carrots, and tomatoes, specimens of the wildflower species Tradescantia paludosa, three strains of the single-celled green algae Chlorella, and one strain of lysogenic bacteria. Despite a very rocky re-entry to Earth’s atmosphere and a rough splashdown in the Indian Ocean, the entire biological payload was successfully recovered, demonstrating that complex organisms could withstand the extended trip in space and a lunar flyby.