The Shiva Purana depicts Lord Siva’s nirguna aspects as Jyoti Linga. The Lord therefore is beyond all forms. His manifested form is a cosmic riddle. Shaivism contends that all forms proceed from Siva’s non-form and exist in His non-form. Bhaktas give a maanasika attributes, mind form to Lord Siva and His Jyotir Linga. For a while the mind synthesizes a duality of the Lord. The visualized Deity and Jyoti or flame are major manifestations of the Lord to progressively move to the Unmanifest form. That is the highest Truth, the brightest Light.
The manifest form of Jyotir Linga would encompass Parvati being seated on the left while the coiled serpent of the kundalini chakra is awakened; the panchabhutas or five cosmic elements as represented by the five Sadasiva images and the upward Light of the Linga. In all the Jyoti represents all the major twenty forms of Lord Siva. ( Most of these have been posted).
After-all Siva with attributes is also a lila of the Lord to provoke spiritual progress. The murthi would sink to the oblivion sooner than a bhakta can envisage and does not stand to be the intermediary between bhakta and Lord Siva. Over time one sees beyond symbolic images to be aware of Nirguna Siva. That would be the awareness of the reflection of Jyoti shining within.
Hara Hara Mahadeva.