Jelly on the beach

The beach is strewn with blobs of clear jelly. Not jelly fish. Something else. I look at them and wonder, certain I should know what they are. I inspect them closely, noticing the consistent shape across all of them, noticing the horseshoe-like curve. There are many, all washed up on this one section of beach. I take photos, in case my memory loses the details. I keep walking, thinking. Some sort of egg or egg case, I think. But what? It niggles at me. Yet another gap in my knowledge of things marine.