unoperculated
/(ˌ)ʌnˌəʊˈpəːkjʊlətɪd/ /(ˌ)ʌnˌɒˈpəːkjʊlətɪd/Zoology
adjective
Having no operculum.
Origin
Early 19th century; earliest use found in Philosophical Transactions of the Royal Society of London. From un- + operculated, perhaps after scientific Latin inoperculatus inoperculate.