Suppose that a meteorite crashes into Earth and a sample of it is taken to a local research lab for analysis. Embedded several inches within the rocky structure, a microscopic cluster of dormant, spore- like structures is found. The scientists culture some of this material in a standard microbiological nutrient broth, and they are surprised to find many single- celled "organisms" moving around, growing, and reproducing in the broth. The "organisms" behave the same in both daylight and dark conditions, do not require oxygen, and thrive under a wi range of temperatures and pH levels. They stop moving, growing, and reproducing, however, when fewer nutri available in the medium. In this scenario, the "organisms" most closely resemble a(n)