The Neethian cradlefish was an organism.
It was somewhat similar to Earth's terrestrial earthworm, in that any portion of its body which was severed continued to live for a time as an independent organism. In 2152, Doctor Phlox compared the two lifeforms to a symbiotic lifeform Enterprise NX-01 had been infected by. (ENT: "Vox Sola")
According to Star Trek: Star Charts (p. 44) and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), there was a star system named Neethia (Xi Pegasi), which might possibly be the system of origin for this species, in the Alpha Quadrant. The primary was a G-class star and the secondary was a M-class star. This system was a destination on a Denobulan trade route in the 22nd century.