▁extr ater rest rial ▁artifact . ▁ ▁Other ▁authorities ▁have ▁suggested ▁that ▁the ▁object ▁photograph ed ▁by ▁the ▁El tan in ▁was ▁an ▁unusual ▁car n iv orous ▁sp on ge , ▁Ch ond ro cl ad ia ▁conc res c ens ▁( former ly ▁Cl ador h iza ▁conc res c ens ). ▁ ▁History ▁The ▁ 1 , 8 5 0 ▁ton ▁disp lacement ▁El tan in ▁was ▁originally ▁launched ▁in ▁ 1 9 5 7 , ▁and ▁served ▁with ▁the ▁US ▁Navy ▁as ▁a ▁cargo - car ry ing ▁ice bre aker . ▁In ▁ 1 9 6 2 ▁she ▁was ▁rec lass ified ▁as ▁an ▁Ocean ographic ▁Research ▁Sh ip ▁and ▁became ▁the ▁world ' s ▁first ▁dedicated ▁Ant ar ctic ▁research ▁vessel , ▁a ▁role ▁which ▁she ▁filled ▁until ▁ 1 9 7 5 . ▁ ▁On ▁ 2 9 ▁August ▁ 1 9 6 4 , ▁while ▁engaged ▁in ▁taking ▁sample ▁cores ▁and ▁photograph ing ▁the ▁se ab ed ▁west ▁of ▁Cape ▁Horn , ▁the ▁El tan in ▁took ▁the ▁photograph ▁reprodu ced ▁in ▁this ▁article , ▁at ▁position ▁ 5 9 : 0 7 ' S ▁ 1 0 5 : 0 3 ' W , ▁in ▁a ▁depth ▁of ▁ 3 , 9 0 4 ▁metres . ▁▁ ▁The ▁first ▁public ▁mention ▁of ▁the ▁unusual ▁subject ▁of ▁the ▁photograph ▁was ▁a ▁news ▁item ▁which ▁appeared ▁in ▁the ▁New ▁Zealand ▁Her ald ▁on ▁ 5 ▁December ▁ 1 9 6 4 , ▁under ▁the ▁heading ▁"