It often occurs as a "post mine" encrustation on old underground mine surfaces. Bird knew that alkaline urine encouraged phosphate precipitation and the consequent encrustation and stone formation. The main complications with ureteral stents are dislocation, infection and blockage by encrustation. A strong needle was used to pick off the encrustation, revealing the underlying features. For example, metals from shipwrecked sites can have encrustation, which means they contain coagulates. In fact, barnacle encrustation negatively influences swimming in "C. hastata". Decay, corrosion and marine encrustation are inhibited or largely absent in cold waters.