tetrapod
A concrete wave breaker, shaped like a huge caltrop or jack. The edges are typically rounded, but don't have to be. They're used in large numbers in breakwaters, seawalls, etc. to protect against beach erosion.
Example
A concrete wave breaker, shaped like a huge caltrop or jack. The edges are typically rounded, but don't have to be. They're used in large numbers in breakwaters, seawalls, etc. to protect against beach erosion.
