Definition: Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. [ https://en.wikipedia.org/wiki/Silt ]
Definition: Gravel is an environmental material which is composed of pieces of rock that are at least two millimeters (2mm) in its largest dimension and no more than 75 millimeters.
Definition: a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure
