A common nail disorder is an ingrowing toenail (onychocryptosis). The tail lamps were also criticized as looking like "ingrowing toenails". Rather, the urogenital part of the cloacal membrane separates the ingrowing sheets of mesoderm. Fungi ingrowing dead wood are essential for xylophagous insects (e.g. woodboring beetles). Contamination can occur from soil, miscellaneous sediment, construction debris, ingrowing vegetation, and so on.