clam up vi phrasalphrasal verb, intransitive: Verb with adverb(s) or preposition(s), having special meaning and not taking direct object--for example, "make up" [=reconcile]: "After they fought, they made up."
When asked about his personal life, he really clammed up.
riccio di mare
sea urchin nnoun: Refers to person, place, thing, quality, etc.
spina di riccio
sea urchin spine nnoun: Refers to person, place, thing, quality, etc.