Benzohydroxamic acid (BHA) can cause sea urchin eggs to be fertilized by multiple sperm at once. The more BHA and sperm there are, the more likely this is to happen. BHA doesn't slow down the eggs' protective reaction, but it needs to be added before the reaction is finished. Sea urchin eggs release a chemical called H2O2 during this reaction, and the sperm enzyme helps stop too many sperm from fertilizing the egg.