abstract casing external firm hard hardy inside natural nature outside plants rough seedpods seeds shape shaped shapes shell Sizes smooth surface surfaced surfaces surfacing tactile texture textured textures two-sided variations woody wrinkled wrinkles appearances architectural architecture background basic brick-wall bricks building cement color colors colour colours cream mortar perspectives secure solid standard strength traditional-brick-wall wall wallpaper walls activity ants Australian circle circular colored coloured compacted cone conical cracked cracks crater craters entrance grains grainy insects nest round sand sandy Soil symmetrical symmetry abundance angles appearance lifted loose pavers paving paving-bricks plenty quantity rows stacked stacks strong