trilobite

n extinct sea animal found as a fossil 三叶虫（已绝灭的海洋动物, 仅存化石）.

triennial, triennially, trier, trifle, trifler, trifling, trigger, trigger-happy, triglyceride, trigonometric, trigonometrical, trigonometrically, trigonometry, trike, trilateral, trilaterally, trilby, trilingual, trill, trillion, trillionth, trilogy, trim, trimaran, trimmer, trimming, trinitrotoluene, trinity, Trinity Sunday, trinket, trio, trip, trip sb. up, trip-wire, tripartite, tripe, triple, triplet, triplicate, triply, tripod,