...The Natural History Department met last evening--Mr. Gilbert Langdon Hume in the chair. Among the specimens presented were the following:...By Mr. Walters, the spawn of the periwinkle, from Coney Island. These minute shells were contained in a substance resembling dried vegetable matter, about three inches in length, and of a spiral shape. It was stated that they were always thus found ; and some doubts arising as to the nature of the substance, it was referred to Mr. Bell for investigation.
--Brooklyn Eagle, Thursday, November 20, 1845
They are not talking about a flower, but mollusk eggs! There's a fascinating article from 1881 in Harper's Young People. (The author appears to be discussing a walk from near the aquarium and west towards the main stretch of Coney, on toward Sea Gate.)
WONDERS OF CONEY ISLAND.
BY A. W. ROBERTS.
IF grown-up folks and young people who are desirous of becoming acquainted with the marine wonder-land of Coney island will take a stroll along the beach, starting from the Iron Tower and proceeding a mile toward Norton's Point, I'll promise them that their constant exclamations will be, "I wonder what it is!" as they meet with one after another of the many curious marine objects that are to be found along the two upper lines of drift...
Fig. 10 is a string of the egg cases of the periwinkle shell, which is one of the largest shells inhabiting the waters of Coney Island. The eggs are contained in a soft leathery case of a light yellow color, about the size of a two-cent piece, but much thicker. Each case contains from one hundred and fifty to two hundred eggs. These strings of eggs vary from one to two feet in length.
--Harper's Young People, Volume 2, 1881