These are Fossil Coral Jasper Lingam from India.Fossil Coral is a natural type of gemstone formed by ancient corals.The proper name for fossil coral is ‘Agatized Coral’ or 'agatized fossil coral', because during formation, the coral remains are gradually replaced with Agate, a variety of naturally occurring Chalcedony, or microcrystalline quartz. When prehistoric corals are fossilized through replacement with agate, the fossil coral forms through hardened deposits left by silica-rich waters.
The entire process can take over 20 million years and occurs only under very unique geological conditions.
Corals are marine animals and it is their skeletons that are fossilized and preserved, often leaving flower-like patterns in the stone.
Fossil coral should not be mistaken for endangered or protected reef coral or Precious Coral.It is considered to be a type of agate or chalcedony, rather than a type of coral, due to its silicon dioxide composition (SiO2). Coral deposits have been mined and commercialized for their high calcium, potassium, magnesium and sodium content, and are often used for the making of health and drug supplements. Fossil coral is used in industrial fertilizers and water purification filters because it can remove chemical impurities such as chlorine and formaldehyde.