Wormlike limestone contains spheroidite like worm, hence the name.

The wormlike limestone in the geopark mainly distributes in the strata of Lower Triassic Zhenning Formation, especially it develops most in the first and third members. The structure is composed of two parts, namely, dark grey and ash black worm body and light grey matrix. Most worm bodies are small, 6-10mm in length, 1.5-2.5mm in width and 2-3mm in thickness, which distribute densely. They are in granulous, pisolitic, tubulose, long striped, rhizoma nelumbinis, and irregular granulous as well as strip shape. Upon rock-mineral determination, worm body is the syngenetic scraps of organic matter and calcite binders polluted clay in fact. It went through sedimentary differentiation under special thalassochemistry condition in early triassic, then upon synsedimentary diagenesis and macro body organisms and microorganism function at different degrees, thus subreticulate and parallel arranged synclase were generated on the rock, and the rock was divided into lots of syngenetic scraps before its formation.
 
Wormlike limestone (the right one is observed microscopically)