When beachcombing in the Bahamas I discovered a number of mostly round, about quarter size, water filled, and plastic-like outside objects. I brought one of the odd objects to my professor and he informed me that they were a kind of algae (Ventricaria ventricosa) known commonly as sea pearls (also called bubble algae and sailor’s eyeballs). After recovering from the guilt of poping a whole bunch of sea pearls, thinking they were some kind of trash, I researched more about them. And in case you were wondering, they poped kind of like a water balloon. They were filled with water and not much else. Their cell wall was very plastic like and rubbery. Sadly, they did not resemble a large version of the classic plant cell you learn about in biology class.