Head Dress
Śiva's head-dress incorporates His matted hair. And Gaṅgā, the sacred river on His head is recognised as a symbol of "knowledge." A reference that is immediately recalled is a verse of Śaṅkarācārya viz. Kāśīpañcaka 5: vyāpinī jñānagaṅgā.
Atop the right ear is a floral ornament, suggestive of a serpent. It is in all probability an atasī flower (Linum usitatissiumum or common flax) or palāśa (Butea monosperma). Above the same is an arka flower (Calatropis gigantea) in three layers. Moving further on, we notice a serpent, its hood open. Between the serpent and the left ear, there is a single-digit crescent moon. Serving as a backdrop to all the objects of the head-dress is a crest of peacock plumes. The fifteen plumes of Śiva's head-dress visually allude to the flames of the prabhāvali.
The association of Śiva with the Crescent Moon is well known; here the arka flower and the peacock feathers complement the moon, with the three images forming a coherent tripartite symbolism. The arka is so named because it is "of the Sun." See for example, Bhagavad-gītā 11.17; Śrīmad Bhāgavatam 1.7.30; 1.11.27; 2.5.30. The peacock is also known by the term śikhī, which also means "fire," the word śikhā standing for tuft/ summit/plume/ray/flame/peacock's comb. Thus these two symbolise the Sun and the Fire; and along with the Moon, they form a trinity of luminaries, reinforcing the symbolism of Śiva's three eyes. The Tantra texts regularly refer to the Sun, the Moon, and the Fire as representing Brahmā, Viṣṇu, and Rudra, symbolising creation, maintenance, and destruction. For example, Śāradātilaka 12.93:
śabdārtha-bhāvi-bhuvanaṁ sṛjatīndurūpā /
yā tad bibharti punararkatanuḥ svaśaktyā |
vahnyātmikā harati tatsakalaṁ yugānte /
tāṁ śāradāṁ manasi jātu na vismarāmi ||
शब्दाऽर्थ-भावि-भुवनं सृजतीन्दुरूपा /
या तद् बिभर्ति पुनरर्कतनुः स्वशक्त्या ।
वह्न्यात्मिका हरति तत्सकलं युगाऽन्ते /
तां शारदां मनसि जातु न विस्मरामि ॥
Even this verse was very dear to Śrīraṅga Mahāguru.