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Saw this beautiful nest structure in sand at the bottom of a canyon, about 20 to 30 ft from the river. Tunnel went straight down several inches and may have turned after that. Chimney is neatly arranged debris held together with silk-like substance. Accidentally destroyed the chimney while investigating. Much to our joy, the hole was re-excavated and the chimney rebuilt with new materials over the course of a night. What is it? Spider?