硬壳

incrustation

硬的英语翻译：

firm; forcedly; forcibly; good; hard; rigidity; stiff; strong; tough
【医】 pachy-; scirrho-

壳的英语翻译：

carapace; hull; rind; shell; shuck
【化】 cover
【医】 crust; crusta; crustae; putamen; shell; testa