ancient black celtic classic design groningen illustration knot pattern red shape vector white background border construction culture decoration geometry graphic knots lay-out layout square carved curled decorative helix intertwined intricate ornament ornamental shapes snail snake symbol symbolism wooden backdrop celt close close-up closeup cultural curve curved detail detailed details free gray grey image kelt keltic knotted macro old patterns photo photograph picture primitive resource rock rocks rocky somadjinn stock stone stones texture textured UP weave weaving woven