subumbrella
Noun
Meaning
The integument of the under surface of the bell, or disk-shaped body, of a jellyfish.
Source: Webster's dictionaryAnagrams
Examples
Most have tentacles around the outer margin of the bowl-shaped bell, and long, oral arms around the mouth in the center of the subumbrella.
The upper or aboral surface is called the exumbrella and the lower surface is called the subumbrella; the mouth is located on the lower surface, which may be partially closed by a membrane extending inward from the margin (called the velum).