Procedure:
Open the urchins and with the utmost care, remove the pulp with a teaspoon and set aside in a separate bowl. In a pan, gently fry the garlic and chili then adding the tomato which you have sliced in half.
When these have softened add the pulp from the urchins and fry vigorously just for a minute.
In the meantime, boil the spaghetti and after having drained them, add them to the pan with the urchins sauce, adding the parsley.
Toss the spaghetti into the sauce until it is well mixed, adding extra virgin olive oil and salt to taste.
Serve hot.

Variation:
You may also add 200g of fresh black mussels, opened and adding these together with their sea juices into the pan at the same time as you have added the tomato's, and before having added the urchins.