One of Ecuador's greats, conchas negras or black clams are everywhere, piled up in heaps just waiting to be cracked open by your friendly vendor and served with a good squeeze of lime. If you want to go a little further, try a full-fledged ceviche de conchas negras, which has added onion and parsely, depending on who's making it. During peak summer and tourist season, the whole strip is buzzing, but get down to the market, sit down on the inevitably creaky wooden stool and tuck into a bowl of these delicacies. Although some restaurants and sellers don't respect it, there is a ban on the harvest of conchas negras from the 15th of Feb to the 31st of March, to allow this precious and increasingly under-pressure mangrove mollusc to recover.