The Leafy Seadragon, Phycodurus eques, from southern Australia (Wikipedia)

Post-Performative Post-Scriptum

Wikipedia says: “The generic name is derived from the Ancient Greek words φῦκος (phûkos) ‘seaweed’, and δέρμα (dérma) ‘skin’.” That’s obviously wrong for dérma, but I can’t find a definitive etymology.