BELEMNITE

Characteristics of the mineral.

Belemnites - completely extinct detachment of cephalopods. Sometimes their shells are called a "fucking finger." They are related to modern octopuses, cuttlefish and squid, possessed a powerful internal shell - rostrum. In modern squid and cuttlefish, the inner shell is reduced to thin plates, and in Belemnites it was a shell, and quite powerful. It is the rostra you can see in the photos. The belemnite ridge was at the end of the soft body and served as a ballast so that the animal would not turn over and would not wag while driving (rapid jet movement was carried out by the rear end forward by discharging water). On some rostra, it is possible to consider the imprint of blood vessels, which proves their internal location in the body of the mollusk.

The propagation time is carbon-chalk. Active predators. Judging by the number of rostra in the Jurassic strata, they led a lifestyle resembling that of modern squid - swam in huge flocks of individuals of the same size and age. Like the ammonites, they mostly did not survive the era of extinction at the end of the Mesozoic. Although, one of the few genera of belemnites lived in the Paleogene, but this was clearly the last representatives of the detachment. Belemnites are not as beautiful as ammonites, and their growths differ little from each other. The size of the rostrums is from 0.5 to 15 centimeters. They are found in Jurassic clays together with ammonites, but they are better preserved due to greater strength. Sometimes on the rostra there are traces of drilling and eating out by detritophages, so the rostra lay for a long time at the bottom and some bottom animals slowly populated it.

Belemnite. In common speech it is called a fucking finger, a thunderbolt, followed by a lightning bolt. Refers to "ink fish" - two-nimbus cephalopods cephalopods. It is very widespread in the Jurassic and Cretaceous periods. The cone-shaped pointed lime rostrum is the solid rear end of the "ink fish". Meeting in large clusters in the deposits of the Jurassic and Cretaceous periods, belemnites are partly rock-forming organisms. Rosters are usually poorly distinguishable, so that the exact species definition of belemnites is usually difficult. On the rostra, a weak longitudinal groove that does not reach its end - this is characteristic of belemnites from other formations.

The photo below shows the pellets of belemnites found in the sand. These belemnites are of sedimentary origin. Initially, the growths were accumulated at the bottom of primitive seas and oceans of the Jurassic and Cretaceous periods, when belemnites were extremely common. Later, the growths of Belemanites were condensed, covered with layers of other sedimentary rocks and silt, undergone rock-forming changes, then they came to the surface in places.

If the growths were accumulated in large quantities and greatly modified, it can be difficult to separate them from each other - they form solid sedimentary massifs. Where the belemnite growths are not weathered and located in the thickness of the parent rock and are separated from each other, they are very well preserved and have the characteristic shape shown above.

If, however, the belemnites in the rock were weathered (the rocks were washed out by rivers and seas), the growths turned out to be pelletized water, transferred to another place, and acquired characteristic smoothed configurations. The sharp edges and sharp tip disappeared, in many cases even a characteristic longitudinal groove is erased. The water mechanically destroyed and transferred the belemnites to a new location, most often in clusters of sand and other similar material of sedimentary origin. Solid fragments acquire characteristic roundness after 10-20 km of transfer along the active river (for more tranquil rivers more mileage is required). Some fragments scratch others and pellet each other. So they accumulate along the banks of rivers, where the current slows down its course, the mass of pellets obtained from the rostra of primitive belemnites. In fact, the same thing happens with them as with sea or river pebbles. The river and the seas are like pelting stones, belemnites or glass shards. Belemnites along river banks are weathered sedimentary rocks.

This is not the result of sand melting when lightning hits it - fulguriths, since the latter are more like tektites (the results of meteorite impacts on sandy ground) and have a more irregular shape. There is also a longitudinal groove characteristic for the belemnites along the rostra.