18th century Geislengen sets feature Sea-Horses as knights. A similar chess set, dating from 1760, is featured in the excellent Schach Partie Durch Zeiten und Welten, published by Edition Braus in 2005 ( a recommended reference book for serious collectors). This is a relatively rare chess set: a few survive with their original pine boxes.
A lovely original and early set from a major chess collection. Recommended.