anomalous murex

There is a controversy about this specimen. Before 1970, the size of a mature specimen was, on the average, around 2 inches. These are from 4 to 5 inches. I collected it around 1975. People who were experts on marine molluscs say that this may be a fake, i.e, that it is plastic. The epitonium scalare, the channeled wentletrap was also considered a rice paste fake, because of its rarity, until other specimens were discovered. This is from the 1970's. I have stopped collecting for environmental reasons. If there is any clarification on the veracity, please inform me. I have tried to test if it is plastic or not. It doesn't seem to be, but I may not be qualified to test this.