The sand spikes were found near Mount Signal, CA and they are approximately 3 plus inches in length, and weigh from 3-6 oz. each. This area where the sand spikes were found has been depleted for many years. The image shows 3 different sand spikes, but only one will be in an order. Since the sand spikes vary in shapes, it helps to get an idea on what they may look like. The sand spikes from Mount Signal are very rare and hard to come by now except in collections. Our relatives mentioned when the sand spikes were found, all the sand spike blades were laying in a westerly direction. Still, not much is known on how these unique concretions/ sand spikes were formed.