St Ninian's Isle is not actually an island as such, being linked to the Mainland by a deliciously inviting sandy causeway with sea on either side: the correct name for this type of coastal feature is a "tombolo". The island has a chapel on it which lies on a site which goes back much farther than the present building. Excavations at the chapel have revealed ancient burials as well as a treasure trove of Pictish silver objects and the jaw-bone of a porpoise which were buried under a slab near the altar. The silverware, which includes bowls and items of jewellery, was discovered by a schoolboy who was helping the archaeologists, and dates from around 800 AD. The pieces are currently on display at the National Museum of Antiquities Scotland, while the Shetland Museum holds replicas.