The cluster of 9 islands off Istanbul in the Sea of Marmara have long been known to the Europeans as the Prince or Prince's Islands. The Byzantine were in the habit of exiling the unwanted members of their royalty to the monasteries on them. Hence, their collective name. The residents of Istanbul call them Adalar, meaning "Islands" in Turkish. The 5 largest ones are inhabited, while the rest are not, at least not continuously; the smallest being an oversized rock 300 m across. The largest one, Büyükada (Big Island), which used to be called Prinkipo by the Europeans, has been the subject of at least 2 of my posts (here and here).
One of the first Europeans to write about the Prince Islands was Ogier Ghiselin de Busbecq, the Austrian Emperor Ferdinand’s ambassador to the Ottoman Sultan Süleyman the Magnificent in the mid-16th century. During a plague epidemic in Istanbul in 1561, Busbecq spent 3 months on Büyükada. In one his famous Turkish Letters, he wrote about his fishing expeditions off the islands:
Among the rest there is a small island, which is uninhabited*. Close to it I recollect capturing monstrous and extraordinary creatures, such as starfishes, razorshells, clusters of cuttlefish eggs, sea-horses, enormous snails, and some yellow balls like oranges, but no fishes, except one skate or sting-ray, which is capable of inflicting a serious wound with its sting.Everything on Busbecq's list is identifiable (although I am not sure of the species of the "enormous snails") except the orange-like yellow balls. What were they? I am not familiar with the underwater life around the islands, but I suspect they may have been sponges of some sort.
*Probably Kaşıkadası, the Spoon Island, so called because of its shape. It is the 2nd smallest island. Google Earth shows a couple of buildings on it.