From semi- + crustaceous. <span class="searchmatch">semicrustaceous</span> (not comparable) partially crustaceous “semi crustaceous”, in Webster’s Revised Unabridged Dictionary, Springfield...
ostreaceous body Hard, thin and brittle. a crustaceous lichen crustaceousness ecrustaceous noncrustaceous pustulocrustaceous <span class="searchmatch">semicrustaceous</span> subcrustaceous...