A mouth-like opening sits beneath the bulbous body where the manubrium or stalk links the body to its streaming tentacles.
From the dailyherald.com
Furthermore, I confidently predict that the length of skin between the chin and the manubrium will show a similar legthening.
From the guardian.co.uk
More examples
The upper part of the breastbone
The sternum or breastbone is a long flat bone shaped like a necktie located in the center of the chest. It connects to the ribs via cartilage, forming the front of the rib cage, and thus helps to protect the heart, lungs,and major blood vessels from injury. The sternum consists of three regions: the manubrium, the body, and the xiphoid process.
Tube bearing the mouth hanging down from the under surface of a medusa
In Collembola, the large median base of the fucula.
The proboscis of a jellyfish: a tubular structure that connects the mouth to the digestive cavity