▁known ▁to ▁occasionally ▁st ray ▁into ▁the ▁lower ▁keys ▁of ▁Florida . ▁ ▁References ▁ ▁External ▁links ▁▁ ▁Prote in ▁sequ encing ▁ ▁An art ia ▁ly tre a ▁at ▁Mark ku ▁Sav ela ' s ▁Le pid optera ▁and ▁Some ▁Other ▁Life ▁Form s ▁ ▁Category : An art ia ▁Category : In sect s ▁of ▁Cuba ▁Category : Fa una ▁of ▁the ▁Sw an ▁Islands ▁Category : T ax a ▁named ▁by ▁Jean - B apt iste ▁God art ▁Category : But ter f lies ▁described ▁in ▁ 1 8 1 9 ▁Category : N ym phal idae ▁of ▁South ▁America <0x0A> </s> ▁" M oment um ▁De ferred " ▁is ▁the ▁fourth ▁episode ▁of ▁the ▁second ▁season ▁of ▁the ▁American ▁science ▁fiction ▁drama ▁television ▁series ▁Fr inge . ▁Screen writ ers ▁Z ack ▁St ent z ▁and ▁Ash ley ▁Edward ▁Miller ▁wrote ▁the ▁episode , ▁and ▁co - exec utive ▁producer ▁Joe ▁Ch app elle ▁directed ▁it . ▁ ▁The ▁episode ▁followed ▁the ▁the ft ▁of ▁cry ogen ically - f ro zen ▁heads ▁by ▁shapes h if ters ▁from ▁the ▁parallel ▁universe ▁in ▁their ▁search ▁for ▁a ▁specific ▁head , ▁while ▁the ▁Fr inge ▁team ▁attempts ▁to ▁prevent ▁this . ▁Meanwhile , ▁Oliv ia ▁strugg les ▁to ▁remember ▁her ▁conversation ▁with ▁William ▁Bell ▁( gu est ▁actor ▁Leonard ▁N imo y ) ▁that ▁took ▁place ▁in ▁the ▁season ▁one ▁finale . ▁" M oment um ▁De ferred " ▁marked ▁the ▁first ▁appearances ▁of ▁guest ▁actors ▁Ther esa ▁Russell ,