The Tythonians were massive, blob-like organisms, sometimes hundreds of feet long. They were glowing green and had an outer membrane that was deeply creased. They had no true limbs, but had two large pseudopods. One pseudopod was shaped like the letter Y, while the other was simply a large tube. They had no vocal cords and communicated with the aid of Tythonian communicators. Tythonians could live for forty thousand years.