abstract background fence four grass green metal quarter texture wire beach coast copyspace lichen post sea wood wooden barbed Nyberg pole protection rust rusty stop summer barbed wire barbwire clouds curl curve danger diagonal gate get off iron no access razor wire security sharp sky stay away stay out barrier hard knot steel chains outdoors secure bamboo post boundary off-limit sunset grid grill industrial mesh metalic barricade plants water wave dune sand grey keep out railings spikes top twisted