While a boulder may be small enough to move or roll manually, others are extremely massive. In common usage, a boulder is too large for a person to move.[from wikipedia]

Concrete is a composite material composed of coarse aggregate bonded together with a fluid cement that hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, such as ciment fondu. However, asphalt concrete, which is frequently used for road surfaces, is also a type of concrete, where the cement material is bitumen, and polymer concretes are sometimes used where the cementing material is a polymer.[from wikipedia]

A single rock with a background that is neither stone nor dirt.

Beachrock is a friable to well-cemented sedimentary rock that consists of a variable mixture of gravel-, sand-, and silt-sized sediment that is cemented with carbonate minerals and has formed along a shoreline. Depending on location, the sediment that is cemented to form beachrock can consist of a variable mixture of shells, coral fragments, rock fragments of different types, and other materials. It can contain scattered artifacts, pieces of wood, and coconuts. Beachrock typically forms within the intertidal zone within tropical or semitropical regions.[from wikipedia]

Rocks found in river beds and along the shore of rivers and creaks.

Ashlar is finely dressed (cut, worked) stone, either an individual stone that has been worked until squared, or a structure built from such stones.[from wikipedia]

Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. The Earth's body of soil is the pedosphere, which has four important functions: it is a medium for plant growth; it is a means of water storage, supply and purification; it is a modifier of Earth's atmosphere; it is a habitat for organisms; all of which, in turn, modify the soil.[from wikipedia]

A balancing rock, also called balanced rock or precarious boulder, is a naturally occurring geological formation featuring a large rock or boulder, sometimes of substantial size, resting on other rocks, bedrock, or on glacial till. Some formations known by this name only appear to be balancing, but are in fact firmly connected to a base rock by a pedestal or stem.[from wikipedia]

Rocks found under water, whether intentionally sunk or naturally sunk.

The glow in the dark stones are made of natural resin,the glow stones are artificial rocks, non-toxic, non- radioactive and odorless. Glow in the dark rocks do no harm to people and can be very safe for children to play. And glow pebbles are harmless to fish.[from amazon]