Humans are not the only ones to use spikes of one kind or another for protection:
thorns
PATTERNS IN THE KAROO NATIONAL PARK
The first pattern is that of thatch covered with wire netting to protect it from monkeys and birds:
Cracked mud in a dip next to the road:
A brick wall:
Remnants of an old stone wall:
Thorns:
Dry grass blowing in the wind:
Something Over Tea 