Lignosagittiae

Lignosagittiae or Lignosagittae is a phylum of extraterrestrial organisms featured on Encyclopedia Galactica of the Orion's Arm science-fiction setting.

First discovered in 3097 AT (51st century CE) on planet Fuego 485 light-years away from the Solar System in constellation Vulpecula; the xenophylum's intelligence has been augmented into sapience, making Lignosagittae 'xenoprovolves' in-universe.

Etymology
‘Lignosagittiae’ is a portmanteau of the Latin words ligno and sagittae. Ligno is the ablative singular form of lignum (meaning ‘wood’), so ligno means ‘made of wood’ or ‘wooden’.

‘Sagittiae’ is actually a misspelling of the word saggittae, the plural of ‘arrow’ in Latin. Despite this misspelling being present in the article’s title, it is actually written correctly few times in the article itself.

Therefore, lignosagittae means ‘wooden arrows’, which is a fairly self-descriptive name. Referring to a phylum, rather than a species, the plural form of their name makes sense, like it does for Porifera or Mollusca on Earth.

Taxonomy
Lignosagittae is an extraterrestrial phylum, so its biodiversity might even rival that of Chordata. Each of these species is known as a ‘gnosag’.

Anatomy
Lignosagittae exhibit bilateral symmetry.

They have a distinct head connected through a neck to their torso, whose dorsal part is protected by an inverted, boat-like carapace. The carapace’s beginning is pointy and ends with a vertical tail. The head possesses two large eyes.

An individual possesses 6 arm-like segmented limbs arranged in 3 pairs, all ending with two claw-like structures. They can be inferred as homologous in evolutionary terms. The frontal pair is named ‘graspers’ and are much bigger than the rest, named ‘legs’, where gills are located on their innermost segment. They are prehensile body parts.

Being aquatic, a lignosagittae individual exhibits 4 paddles for locomotion, organized in two pairs: frontal and rear paddles. The vertical tail at the carapace’s end might confer directionality.

Diet
Being heterotrophic, they feed upon microbial chemotrophic life around hydrothermal vents located deep into the ocean. Since these microorganims organize in mats and exhibit sexual dimorphism, Lignosagittae unintentionally coat their bodies with gametes and transfer them from mat to mat, enabling their reproduction in a symbiotic process akin to how bees pollinate flowering plants on Earth.

Reproduction
Nothing is specified about Lignosagittae reproduction.

Interspecific interactions
Discovered by the Terragen civilization in the 51st century CE, they did not originally consist of intelligent species and their homeworld was declared as a natural reserve some point after.

Their intelligence was nonetheless artificially increased during the first half of the 67th century CE on the neighboring terraformed world of New Charon by the Terragen clade Genen. After that, lignosagittae were even invited for membership in the Zoeific Biopolity. However, they turned down the offer to begin a relativistic travel towards the Ring Nebula (Messier 57) in constellation Lyra.

Since their vision adapted from the depths of the ocean to those of space, the colorful nebula lured their subconscious like the hydrothermal microbial mats once did.

An individual named Harld Seeger invited numerous gnosags to live in Panthalassa, and they accepted.