Nautroid

I don't know, it just looks like another rock through the signalscope... By the Tides! It has tentacles!

The Nauroid (Astronautilus Peralith) is one of the most ubiquitous species of spacebourne Xenofauna found across the galaxy. These strange molluscs are easy to mistake for a starship's systems to mistake them for asteroids at long ranges, which is not helped by the fact that their shells tend to slowly accrete space dust and small rocks, forming the cores of asteroids over the course of millions of years. Upon closer inspection, however, they bear a close resemblance to the aquatic Terran nautilus.

Voidbourne Molluscs

As with all spacebourne Xenofauna, it is still unknown exactly what metabolic processes allow Nautroids to live in the oxygen starved vacuum of space. It is believed that their large "sail" tentacles double as solar collectors allowing for some process akin to photosynthesis. They still require a carbon source to grow, heal from injuries caused by micrometeor strikes and to repoduce, and as such their main diet appears to be asteroids rich in carbon and other organics.