(covers information from several alternate timelines)
These are an unidentified non-humanoid species observed in the 22nd century.
Akaali horned creature
Akaali long animal
Archer IV wildlife
Klingon food animal
Loracus Prime termites
Mirror universe animal
A bipedal species, from an unknown star system.
This species, and their technology were unknown even to the Vulcan database. They chased the Enterprise NX-01 in September of 2151, and did not respond to hails. Then they returned several other times, now causing significant damage. During one attack, this species activated a dampening field, while two of its crew boarded Enterprise. They were fired at by Captain Archer, but the phase pistol had no effect. They soon left. (ENT: "Silent Enemy")
The species was designed by Dan Curry. John Teska, who built the CGI models, referred to the aliens as "Shroomies" after their mushroom-shaped heads. Other members of the art department, such as Doug Drexler, also used this name. Teska commented on his build, "Some fans out there must know the name of the mysterious aliens from "Silent Enemy", but I'll only know them as ‘the Shroomies'. These lovely bulbous-headed beauties appeared in first season "Enterprise" and were featured in several shots sneaking around the ship and scanning an unconscious human. I recall Dan Curry brought these sketches and we discussed ways to make their appearance and actions non-human – there should be no mistaking them for actors in costume. I had fun fleshing them out in 3D from the pencil drawings. The skin surface had layers of organic texture as if their heads were filled with organs. You probably would not enjoy eating dinner with one if you were invited… which is very rare indeed." Curry later remarked, "I had the opportunity to design the alien creatures. I worked with John Teska up at Foundation Imaging. I wanted their skin to be somewhat transparent, like those fish where you can see their internal organs. John did a great job in creating a creature like that, where it's almost like a jellyfish on the outside and you can see the nerves under the skin. I was very happy with those."(Star Trek: The Magazine Volume 3, Issue 7, p.52)
Skagaran colony creatures
Spiked pig-like animal
Xindi Biorifle lifeform
The power source of a Xindi-Reptilian biorifle was formed by an eel-like engeneered lifeforms. These creatures were capable of reproducing, and thrived when exposed to omicron radiation. However, a sustained burst of delta radiation could kill the creature. (ENT: "The Shipment")