What is a menstrual sponge?

A menstrual sponge is a sea sponge, which is an aquatic organism made of a substance called spongin. Sea sponges are living organisms that attach to underwater surfaces and continuously filter sea water to support their organic functions.

Sea sponges are incredibly absorbent, and they expand to retain the liquid inside of them. Some companies market sea sponges as a natural alternative to other period products. These companies claim that menstrual sea sponges can be used similarly to a tampon, rinsed, and reused for six to twelve months.