Caryophyllidia are an anatomical feature of the external dorsal surface of
dorid sea slugs. Caryophyllidia are sensory
tubercle
In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal.
In plants
A tubercle is generally a wart-like projection ...
s, surrounded by tiny needle-like structures called spicules, that are present on the outer
mantle.
References
Gastropod anatomy
{{gastropod-stub