What is radula and in which phylum it is present?

Radula:

1. The radula is a rasping structure for feeding present in almost every class of Mollusca.
2. The radula is absent in class Bivalves of phylum Mollusca.
3. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before food enters the esophagus.
4. It appears as a ribbon-like structure with many denticles.