Which group of echinoderms uses tube feet to pry open bivalves?

A flowering plant with parallel leaf veins and petals in multiples of three is likely a:

Mitochondria are known as the “powerhouse” of the cell because they:

Animal cells have cell walls; whereas plant cells do not. 

Where have bacteria been found living?

What is the Precambrian Supereon known for?  

Evidence supporting the endosymbiotic origin of mitochondria includes:

What would forests look like without decomposers like fungi?

Are bacteria and archaea unicellular or multicellular?

What is the main structural difference between prokaryotic and eukaryotic cells?