Simplify the following text for a Grade 8 native English-speaking person.
Original: It is formed entirely from hexagonally jointed basalt columns , similar in structure to ( and part of the same ancient lava flow as ) the Giant 's Causeway in Northern Ireland and those of nearby Ulva .
Simplified: It is formed entirely from hexagonally jointed basalt columns . These are part of the same ancient lava flow as the Giant 's Causeway in Northern Ireland and those of nearby Ulva .