Does anyone know what kind of bird might have built this nest? It's nearly a perfect sphere with a little entrance tunnel pointing downward at the front. The whole thing has the general shape of a retort beaker from a chemistry lab. It measures about 4.5 inches in diameter, and the entrance is about 1.5 inches wide. The location is in the vicinity of Corpus Christi, Texas. The area is kind of a mix of prairie land and chaparral-ish scrub brush. The nest itself is at the edge of some thick brush on a bluff directly over a shallow salt water bay. It really has me perplexed. I wonder if I might have to join a birding site to find an answer.