Floatstone is a term used to describe lightweight rock formations that have been formed from the accumulation of organic materials. Other synonyms for this type of rock include pumice, scoria, and tuff. Pumice is a type of volcanic rock that is known for its lightweight and highly porous structure. Scoria, on the other hand, is formed when molten lava is ejected from a volcano and then rapidly cools, leaving behind a porous and lightweight rock. Tuff, which is also known as volcanic ash, is formed when volcanic ash is compacted and cemented together. All of these rocks share similar characteristics to floatstone and are often used interchangeably.