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 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.
Left)Echinometra lucunter, Middle) spinesin the feet of bathers, Right) hyperkeratotic noduleson the hands
Mediterranean black sea urchin sting being expelled from the body by itself after three weeks