Translucent polyp

Some polyps are covered by mucosa that is opaque. Some are filled with blood (hemorrhagic polyp). On the other hand, some have a thin and delicate mucosa, and a watery content that is not transparent, yet transmits some light. Unlike a blister, which they could be construed as resembling, and which typically resolves itself, most translucent polyps end up requiring surgery for their resolution.

Photos of translucent polyps: