Ceratophyllum echinatum

Ceratophyllum echinatum, known as prickly hornwort, spiny hornwort, or spiny coontail, is an aquatic, perennial plant found in North America. Its name comes from fruits, which have a warty surface and long spines. Spiny hornwort can be found in ponds and lakes, principally in eastern North America. It is the only species of its genus endemic to North America. Ceratophyllum comes from the Greek keras, "a horn" and phyllon, "leaf", which is alluding to the stiff and narrow leaf divisions. The specific epithet echinatum comes from echinus which means sea urchin or hedgehog....read more on Wikipedia.