How do index fossils help scientists?

Which organisms have pharyngeal arches that develop from all three germ layers and go through the same development stages as embryos? 1.bird 2.ladybug 3.starfish 4.snake

Ateam from new york presbyterian hospital is conducting a study about a recent increase in cases involving both excess sweating and kidney stones. what would the team need before it draws a conclusion about the cases? medications that are specifically designed to treat the sickness machines that are built to process blood and reduce symptoms until patients are healthy again data that profile the various patients who report these symptoms proof that the excess sweating is related to the excessive kidney stones

What is it called when lava when it erupts from the surface through volcanoes.