Can you tell the age of a sea urchin by the number of spines it has?

Unfortunately, determining the age of a sea urchin by counting its spines is not an accurate method. Sea urchins are unique creatures that have the ability to regenerate their spines throughout their life, which means the number of spines can vary significantly from individual to individual.

However, determining a sea urchin's age can be done by examining the growth rings on their teeth. Like the rings on a tree trunk, a sea urchin's teeth will develop growth rings over time that can be counted to determine their age.

Scientists have found that the growth rate can vary depending on several factors including temperature, food availability, and water quality. With all these variables, it is hard to determine the exact age of a sea urchin accurately. In most cases, scientists just estimate their age, but the best and most accurate way to know this is to examine the teeth under a microscope, which can reveal the number of growth rings and therefore, the age of the sea urchin.