Simplify the following text for a Grade 9 native English-speaking person.
Original: The spiral plays a specific role in symbolism , and appears in megalithic art , notably in the Newgrange tomb or in many Galician petroglyphs such as the one in Mogor .
Simplified: The spiral plays an important role in symbolism . It appears in megalithic art , notably in the Newgrange tomb or in many Galician petroglyphs such as the one in Mogor .