(CNN) — It is a staggering number, 1.9 million, that is how many pieces of microplastics researchers say are in a single square meter of ocean floor.

It is the highest concentration ever found on the floor of the sea.

Microplastics, small pieces of plastic in products like glitter, exfoliants, and detergents, post critical environmental dangers. They are mainly composed of fibers from textiles and clothing not filtered out in waste water treatment plants.

The lead author of the study says his team was “shocked” by the discovery, he says “garbage patches” of bottles, bags and straws often seen floating on the surface of the water is “the tip of the iceberg.”

Microplastics can be ingested by microorganisms and pass up the food chain.

According to research spearheaded by the University of Manchester, the accumulation of floating plastics accounts for less than 1% of the ten million tons of plastic that enter the world’s oceans each year.

The missing 99% is thought to accumulate in the deep ocean. The study was published Thursday in the Journal Science.