為什麼地中海底的雙耳瓶是尖的?

Collection of amphoras from different parts of the Mediterranean:

Source: https://en.wikipedia.org/wiki/Bodrum_Castle#/media/File:Turkey.Bodrum033.jpg

Wikipedia:  https://zh.wikipedia.org/wiki/双耳瓶
雙耳瓶是一類陶瓷瓶，具有兩隻把手以及細長的頸部結構。雙耳瓶首先在前15世紀出現於今敘利亞地區，然後傳播到世界各地，被古希臘人、古羅馬人用於運送與存儲葡萄、酒、橄欖油、食用油、穀物、橄欖、魚類等。後來，人們生產了一些高品質的手繪雙耳瓶，用於大量社會禮儀用途。這些雙耳瓶不同於其他強調功能的雙耳瓶，裝飾更具藝術性，常被用作獎勵。

Source:  Wikipedia   https://en.wikipedia.org/wiki/Amphora

Amphorae designed for marine transport, taken from shipwrecks of the Bronze Age, on display in the Museum of Underwater Archaeology at Bodrum Castle, Turkey. The museum archaeologists have devised a rack and roping device to illustrate how the cargo might have been kept from shifting.

Amphorae are of great use to maritime archaeologists, as they often indicate the age of a shipwreck and the geographic origin of the cargo. They are occasionally so well preserved that the original content is still present, providing information on foodstuffs and mercantile systems. Amphorae were too cheap and plentiful to return to their origin-point and so, when empty, they were broken up at their destination. At a breakage site in Rome, Testaccio, close to the Tiber, the fragments, later wetted with Calcium hydroxide (Calce viva), remained to create a hill now named Monte Testaccio, 45 m (148 ft) high and more than 1 kilometre in circumference.