See also [[Marine Envenomation]], [[Water-immersed wound infections]] # Penetrating injuries from sea urchins Sea urchins occur throughout Australian coastal waters. Penetrating injuries occur from their spines, usually when people step on them or handle them. Treatment for these penetrating injuries involves removal of the broken spines. Some spines are hard and can easily be removed; however, removal can be difficult if the spines are chalky and brittle. Radiography and ultrasonography are useful to identify retained spines in subcutaneous tissue, and can assist their removal if the spines are close to the skin surface. Review the patient within 24 to 48 hours to enable early detection of infection, then review regularly until symptoms have resolved. If infection is suspected, see treatment. Further imaging and surgical removal of sea urchin spines may be required.