Final answer:
It is true that deeper, closed belly buttons can harbor more bacteria due to their dark, warm, and moist environment, as compared to shallow, open ones that are aerated and less conducive to bacterial growth.
Step-by-step explanation:
It is true that an individual with a deep closed belly button is more likely to have more bacteria compared to an individual with a shallow open belly button. This conclusion is supported by a study titled 'A Jungle in There: Bacteria in Belly Buttons are Highly Diverse, but Predictable' which found that the navel's architecture can influence the bacterial biodiversity.
In a deep, closed navel, the environment is better suited for bacteria to thrive as it is darker, warmer, and moister, compared to a shallow open belly button which allows for more aeration and less accumulation of bacteria-friendly substances such as sweat and dead skin cells.