In a super rare occurrence, conjoined twins born in Indonesia have four arms, three legs and shared genitalia. Such twins are scientifically known as ischiopagus tripus and is one in a two million phenomenon. Just a handful of such conjoined twins, also referred to as 'spider twins', have been recorded - the case of Indonesian boys has been published in American Journal of Case Reports. The twins were born in 2018, but the case was published in the journal this week. "The rarity of ischiopagus tripus conjoined twins complicates the surgical separation, owing to the lack of cases and high complexity," the authors wrote in the American Journal of Case Reports.