I have observed and even practiced the act of breaking a coconut before any Hindu ritual or before starting any auspicious deed.
It is also offered before God after breaking it. What does this signify? What makes coconut so special?
I referred this question. What is the significance of nãrikel (coconut) in pooja?What is the significance of nãrikel (coconut) in pooja? but it seems like the question does not refer to the act of breaking a coconut and its significance.