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 veriety 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. 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 outbut being eaten by microbes that absorb its energy in interplanetary space, and use it as food (a small amount is used as fuel to move the microbe as well). Where they found a microbe at the planet Adrian (at Tau Ceti), which eats the "Astrophage". Eridians brought some of the Taumeoba (the bacteria that eats the other one), back to Erid, and got rid of the Astrophage.