They dissolve your insides, peel the skin off the soft dissolved flesh carefully, and either slide into any large orifice (Such as the Anus or uhh Other parts) Or, create an incision and insert themselves into it, their skin have microscopic octopus-like suckers that Latch onto the inside of the skin, they then secrete compounds that quickly heal the skin from any damage before hand, this removes tattoos, piercings, and other modifications to the skin, and the skin eventually begins to rot.