Can one twin hide behind the other in gestation?

In gestation, one twin cannot physically "hide" behind the other in a way that would obscure its existence entirely, as both embryos develop in the same amniotic sac (in the case of identical twins) or separate sacs (in fraternal twins). However, one twin may be smaller or less developed than the other, which can sometimes lead to difficulties in imaging or assessing the smaller twin during ultrasounds. This phenomenon is often referred to as "vanishing twin syndrome," where one twin is absorbed into the other or the surrounding tissue. Overall, while one twin might be less visible, both are present and developing.