Once in a while the ocean water and wet sand glow when u step on it or move in it. i must know what causes it?

it looks like fairy dust ( or toxic waste) im in corpus christi texas and i havent lived here long but im at the beach day and night almost non-stop and have only seen this twice. its sparkley, glowy, remarkably amazing and i must know why it does that and if it can be predicted when it will do it again?