Why do golden moles have eyes covered by skin and fur?

Golden moles have degenerate eyes that are covered by skin and fur because they are specialized, blind, burrowing insectivores that spend their lives underground or moving through sand.1

Unlike many other mammals that rely on vision, golden moles have evolved to thrive in subterranean environments where sight is not necessary for survival. Their eyes are considered degenerate, meaning they have lost their functional complexity over time as an evolutionary adaptation to their burrowing lifestyle. Covering these vestigial structures with skin and fur provides protection from the abrasive soil and debris they encounter while excavating tunnels or "swimming" through sand.1