A "shell beach" is a descriptive term that is used for sea beach

Beach

A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...

es that routinely (or very frequently) have an unusually large accumulation of seashell

Seashell

A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer created by an animal that lives in the sea. The shell is part of the body of the animal. Empty seashells are often found washed up on beaches by beachcombers...

s washed up on them. Seashells are usually the dead empty shells

Mollusc shell

The mollusc shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes...

 of marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 mollusks, but may also include tests or shells of other groups of animals. Most beaches in the world are primarily composed of rock particles such as sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

, grit

Grit

Grit may refer to:* GRIT , also known as Arhgap32 or PX-RICS* Grit , a U.S. periodical founded as a newspaper in 1882* Grit , by Celtic fusion musician Martyn Bennett* Grit , by Norwegian rock band Madrugada...

, gravel

Gravel

Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...

, pebble

Pebble

A pebble is a clast of rock with a particle size of 4 to 64 millimetres based on the Krumbein phi scale of sedimentology. Pebbles are generally considered to be larger than granules and smaller than cobbles . A rock made predominantly of pebbles is termed a conglomerate...

s, etc, but in rare cases (including Shell Beach in Western Australia) the beach is composed entirely of seashells, both broken and whole valves.

One area in the USA that is famous for its shell beaches is Sanibel Island

Sanibel Island

Sanibel Island is an island located on the Gulf coast of Florida, just offshore of Fort Myers. In 2000, it had an estimated population of 6,064 people...

 on the Gulf Coast of Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

. In South Africa, the beaches of Jeffreys Bay

Jeffreys Bay

Jeffreys Bay is a town located in the Eastern Cape province of South Africa. The town is situated just off the N2 Highway, about an hour's drive southwest of Port Elizabeth.- History :...

 are famous for shells, as is the Sulu Archipelago

Sulu Archipelago

The Sulu Archipelago is a chain of islands in the southwestern Philippines. This archipelago is considered to be part of the Moroland by the local rebel independence movement. This island group forms the northern limit of the Celebes Sea....

 in the Philippines.

As a place name

The phrase "shell beach" has also become a place name for several areas which feature beaches rich in shells:

• Shell Beach, California, a city in San Luis Obispo County
• Shell Beach, Guyana
  Shell Beach, Guyana
  Shell Beach, located on the Atlantic coast of Guyana in the Barima-Waini Region, near the Venezuelan border, is a nesting site for four of the eight sea turtle species - the Olive Ridley, Hawksbill, Green and Leatherback. Shell Beach extends for approximately 140km....
  
  
• Shell Beach, Louisiana
  St. Bernard Parish, Louisiana
  St. Bernard Parish is a parish located southeast of New Orleans in the U.S. state of Louisiana. The parish seat is Chalmette, the largest city in the parish. As of 2000, its population was 67,229. It has been ranked the fastest-growing county in the United States from 2007 to 2008 by the U.S....
  
  
• Shell Beach, Western Australia
  Shell Beach, Western Australia
  Shell Beach is a beach in the Shark Bay region of Western Australia, 45 kilometres south-east of Denham.It covers a 110 km long stretch of coast along the L'Haridon Bight. It is one of only two beaches in the world made entirely from shells....
  
  
• Shell Beach, part of the coastline in La Jolla, California http://www.sandiegocoastlife.com/attractions/san-diego-coast/tide-pools-shell-beach.html
• Barricane Beach, aka Shell Beach, just north of Woolacombe
  Woolacombe
  Woolacombe is a seaside resort on the coast of North Devon, England, which lies at the mouth of a valley . The beach, which has Blue Flag and Premier Seaside Beach awards for its cleanliness, water quality and facilities, is long, sandy, gently sloping and faces the Atlantic Ocean near the...
  
   in North Devon
  North Devon
  North Devon is the northern part of the English county of Devon. It is also the name of a local government district in Devon. Its council is based in Barnstaple. Other towns and villages in the North Devon District include Braunton, Fremington, Ilfracombe, Instow, South Molton, Lynton and Lynmouth...
  
  , England http://www.devonguide.com/beaches/north_devon.htm

Related names include:

• Shell Island (Wales), an island that has a long shell beach

The phrase "shell beach" has also been used as a place name in a fictional context:

• The name of a place in the movie Dark City