Examination involving universal and popular marine creature
I believe the answer is:
sea urchin
'marine creature' is the definition.
(I've seen this before)
'examination involving universal and popular' is the wordplay.
'examination' becomes 'search' (search is a kind of examination**).
'involving' is an insertion indicator.
'universal' becomes 'u'.
'and' is a charade indicator (letters next to each other).
'popular' becomes 'in'.
'search' placed around 'u' is 'seaurch'.
'seaurch'+'in'='SEA-URCHIN'
(Other definitions for sea urchin that I've seen before include "Main thing" , "spineless creature" , "Marine invertebrate - enrich USA (anag)" , "Marine animal with globular body" , "marine echinoderm" .)