Jurassic Floor/ammonites are extinct marine cephalopods. The shape of their shell resembles the curled horns of the Egyptian god Amun - hence the name of these invertebrates. They lived only in the seas. The diameter of most of them was a few or a dozen centimeters. However, the largest specimens were up to 2.5 meters in diameter (!). Ammonite shells became larger as their bodies grew, with females being much larger than males. Their remains occur in sedimentary rocks from the Devonian to the end of the Cretaceous period, i.e. they lived over 160 million years ago. The ice sheet transported them to the vicinity of Łuków. The Jurassic glacier floe is located in Łuków at ul. Żelechowska (in the former brickyard) and in Gołaszyn (Łuków commune). Here, in 1980, the Kra Jurajska reserve was established, where black Jurassic clay containing ammonites was protected. Łuków ammonites were discovered in 1896 by Nikołaj Krisztafowicz during the construction of the Łuków-Lublin railway line. After World War II, research on ammonites found in Jurassic black clays was conducted by Prof. UW Henryk Makowski. Their rich collection can be seen in the Łuków Regional Museum.