The violet sea snail eats By the Wind Sailors, a hydroid a bit like a small jelly fish with a sail. The violet sea snail blows bubbles to stay afloat. It is violet because the hydroids are violet and that’s all it eats. Sometimes the hydroids come ashore in the millions – a mass stranding. Look for the snails then too. The hydroids have sails to the right or to the left so that they won’t all strand at once.