螺 (spiral shell) and 鈿 (ornament) combine with their On'yomi readings to form らでん. 螺は read ラ, not ロ. This term refers to a decorative technique where iridescent pieces of shell, such as mother-of-pearl, are inlaid into lacquer or wood.

螺も鈿も音読みで「らでん」と読みます。螺は「ろ」ではなく「ら」と発音。アワビや夜光貝などの真珠光を放つ部分を研磨し、漆器や木地にはめ込む装飾技法です。