I started reading the Ian Flemming 007 novels a few years back. He often uses this term in a nautical sense. That is small head of coral just above or below the water line that is very hard to spot making it a navigation hazard.
BTW, I too had the reaction that this is more evidence of how deeply his and his family’s roots go into Dim party.
Antique river navigation charts show these same hazards you described and they are named the same. The political correct term of Afro-Enginered that corrected a popular name for a fouled up situation needs to be applied. Please note my PC use of terms and language as the HNIC would probably court martial my ancient arse.