Sea urchin
The spines are long and sharp in some species, and protect the urchin from predators. The spines inflict a painful wound when they penetrate human skin, but are usually not dangerous. Echinoids also have pincer-like pedicellaria all over their body between the spines. The job of these is to deal with anything (like larvae) settling on the test (outer shell).p101 It is not known if the spines are venomous (unlike the pedicellariae between the spines, which are venomous).