Two fossils that I had inadvertently obtained before, readers to see.
Brachiopoda is a sea-born benthic invertebrate. It resembles a bivalve mollusk, but the shells of brachiopods are divided into dorsal and abdominal shells, and the bivalves are two shells on the left and right. The lower shell is usually larger , with a beak-like protrusion and a circular opening on the dorsal side of the posterior end , and its shape is reminiscent of ancient Roman lamps , so the original English name means " lamp shell " . The internal structure is more significantly different from shellfish. It is found in the ocean. There are not many extant species, about 80 genera, 300 species. It was once flourishing, with about 30,000 fossils, about 570 million years ago from the Cambrian period.
The rings are visible
bark
Wood fossils, also known as silicified wood; chemical formula: SiO2·nH2O, belongs to the cryptocrystalline group, hardness: 5.5-6.5, specific gravity: 2.65-2.66, refractive index: 1.54-1.55. It is the trees in the geological history period that undergo geological changes, and finally bury in the formation, undergo chemical exchange and filling of groundwater, so that these chemicals are crystallized and deposited in the wooden part of the tree, preserving the original structure of the tree, and then forming a wood fossil. Silicified wood was mainly formed in the Mesozoic period, with the most in the Jurassic and middle Cretaceous periods.