Final answer:
Based on the description provided, it is likely that the bug found on the couch is something harmless such as a house mite or a dust mite.
Step-by-step explanation:
Based on the description provided, it is difficult to determine the exact type of bug found on the couch. However, given its size and the absence of signs of other bugs, it is likely to be something harmless such as a house mite or a dust mite. Both of these mites are commonly found in homes and feed on organic debris, including human skin.