sea urchin injury sea urchin injury sea urchin injuries are caused by contact with sea urchins, and are characterized by puncture wounds inflicted by the animal's brittle, fragile spines.: 431 sea urchin injury on the top side of the foot. this injury resulted in some skin staining from the natural purple-black dye of the urchin. process sea urchin spines can be venomous or cause infection. granuloma and staining of the skin from the natural dye inside the sea urchin can also occur. breathing problems may indicate a serious reaction to toxins in the sea urchin. following injury by a non-venomous sea urchin, the spine can stay for a while inside the flesh, causing pain and discomfort. the spines dissolve after a time, or are expelled from the body. additional images mediterranean black sea urchin sting being expelled from the body by itself after three weeks