Crawler

Crawlers are an extraterrestrial species of aquatic creature somewhat resembling merfolk, but twisted into a grotesque form. They're considered the most common known species found within Europa's oceans.

Biology
Crawlers possess four pairs of red eyes, green skin, segmented spines on their back and multiple hand-like appendages, with only the frontal ones having a functionality, allowing them to latch on surfaces, swim and crawl (hence their name)., and while individuals are as long as a Human is tall, they're considered one of the smaller species to be found on Europa. They possess three sets of eyes and three legs, accompanied by a set of pincers. Their bodies are covered in a highly-resilient carapace for protection against larger predators, with their head and underbelly exposing their red fleshy skin.

Behavior
Crawlers are hardly ever found alone, Crawlers normally appear in small groups of 1-4 individuals compensating their individual frailty, but they can be seen in large swarms of 8 or 15 individuals in specific, it is theorised that they come in packs in order to compensate their small size

Explorers of Europa often describe shoals of crawlers within the oceans, attacking their vessels and doing combined damage to both crew and their submarines. They have also been reported to have a taste for every type of flesh, including their own, though they rarely attack each other, they will go to an eating frenzy when they spot a corpse of any organic being, including of other crawlers

Velonaceps Calyx
Crawler can also become infected with the Velonaceps Calyx parasite, though it is very rare to find one, it is theorised that before the arrival of human civilitation to Europa, Velonaceps Calyx used to infect Crawlers more regularly to ensure its survival