Nandisvara Island, as per Jain Cosmography, is one of the Island Continents.

It is referred to as Nandisvara-Dvipa meaning continent of rejoicing. “The gods go there to celebrate eight-day festivals sacred to the worship of Jinas, who are honoured with fifty-two bejewelled ‘eternal temples’ (Sasvata-Daivalaya)” – From The peaceful Liberators Jain Art from India by Dr Pratapaditya Pal.

Nandisvara Island is worshipped by both the sects, Svetembara and Digambara, of Jainism. Svetembara sect represents it as fifty-two shrines, four groups of thirteen each. The Digambara sect represents it fifty-two figures of Jina.

The reasons as to why 52 shrines of Jinas is explained in Jaina Rupa Mandana by U P Shah, page 22. I have taken the liberty of including a photo of the relevant portion of the page. See below.

In this example, each side has 13 Jinas divided into two panels. The lower one has one standing Jina surrounded by seven seated Jinas. The top sloping panel has five seated Jina. The sculpture is topped by a finial.

This shrine is about 25 cm in height. It is from Western India and probably from the Deccan region. This shrine may be from the nineteenth century.