3D Model: A Realistic Cave Mesh Shaped Like A Natural Cylindrical Tunnel. The Cave Should Be Completely Enclosed All Around With Only One Entrance/exit, Like A Shelter Or A Burrow. The Interior Should Be Deep Enough To Walk Inside, With Curved Rocky Walls And Ceiling. No Holes, No Skylight, Just A Single Pathway That Goes Inward Like A Narrow Canyon Tube. Think Of A Hobbit Cave, Or A Hidden Animal Den Inside A Mountain. Avoid Complex Branching Paths — Just One Way In And Out. Should Look Natural And Immersive, With Rugged Rock Surface And Believable Scale