Enter measurements for osculum diameter, base CIRCUMFERENCE, and height in centimeters, and hit calculate to estimate the age of the sponge.  Refer to diagrams below for explanation of measurements.

Reference: McMurray, S.E., Blum, J.E., Pawlik, J.R. 2008. Redwood of the reef: growth and age of the giant barrel sponge Xestospongia muta in the Florida Keys. Mar. Biol. 155: 159-171.