Eridian (Project Hail Mary)

The eridians originate from the star 40 Eridiani, and come from the planet Erid. They live in a high heat-ammonia-high pressure atmosphere, similar to Venus but with Ammonia. Eridians have a body shape similar to spiders, with a slab of Semi-biological rock in the center, and have five appendages which are used for a variety of things, such as transportation, similar to a human arm that can also function as a leg. They are slightly behind earth in terms of technological progress. Eridians use echolocation, which is then put into a 3D visualized space in their mind.

Tau Ceti
Their only space mission was to the star Tau Ceti, as a last ditch effort to save their species. Their home star, 40 Eridiani, has its energy output being eaten by astrophage, a single-celled organism that absorbs Tau Ceti's energy in interplanetary space, and use it as food (a small amount is used as fuel to move the microbe as well). Rocky, one of the space project's engineers, found an amoeba at the planet Adrian (at Tau Ceti), which eats the astrophage. Eridians brought some of the taumeoba (the amoeba that eats astrophage), back to Erid, and got rid of the Astrophage.