Lord Shiva Linga Symbol of the Formless Divine

The picture you shared shows a close-up of a Shiva Linga, a cylindrical stone item that is thought to symbolize the formless Shiva.
It is one of the holiest symbols in Hinduism and is frequently revered in Shiva temples.
The Shiva Linga is a symbol of the formless deity, and this is intended to be communicated through the title and description.