Complex sentence: One particular tombstone has a skull and crossbones emblem, and is often mistaken as a relation to pirates (hence the churchyard often being called a pirates' graveyard), however the symbol was once common on tombstones to represent death.
Split into simpler sentences: One particular tombstone has a skull and crossbones emblem, and is often mistaken as a relation to pirates (hence the churchyard often being called a pirates' graveyard). However, the symbol was once common on tombstones to represent death.