List of test materials and their respective elastic moduli. The ability of tentacle-contained cnidocysts from Physalia to puncture these materials is also listed. Note that the elastic modulus of human skin is approximately 0.13 MPa . A positive sign denotes successful penetration of at least some of the threads in all three trials. A negative sign indicates a lack of successful penetration in all trials. In positive cases, thread penetration occurred in all three trials.