Final answer:
The adenoid, or pharyngeal tonsil, located near the opening of the auditory tube, is part of the immune system and helps destroy pathogens entering the nasopharynx.
Step-by-step explanation:
The structure located near the opening of the auditory tube that is part of the immune system is known as the adenoid or pharyngeal tonsil. This tissue is part of the lymphatic system and performs a protective function by capturing and destroying pathogens entering the nasopharynx. The auditory tube, also called the Eustachian tube, connects the middle ear with the pharynx and helps equilibrate air pressure across the tympanic membrane, which is crucial for proper ear function.