Narwhal has a big tooth but no enamel! Randall et al. (2024) analyzed 7 enamel-specific genes in narwhal & other whales and found that 2 enamel matrix genes (AMELX & AMBN) & 2 genes regulating & degrading enamel proteins (ACP4 & KLK4) have been inactivated. https://doi.org/10.3390/genes15020228 #2025MMM