Thai Khom: The spike or "hair" on top of the letters serves a highly functional role. It is often modified or seamlessly fused with attached upper vowels (like the i vowel) to streamline writing fluidly.
Modern Khmer: The spiky crown (called Sawk or Snoeng) remains a permanent ornamental and structural header on top of almost every consonant, giving text its signature jagged upper edge. The Khmer script used today is adapted from the ancient Thai Khom script and dates back only a little over a century.