Thank you for submitting your item for appraisal. This appears to be a terracotta Ampulla Pilgrim Flask of Saint Menas, 6th-7th Century A. D. Apparently with authentic patina and encrustations, possibly found at sea. St. Menas was an egyptian martyr who usually is depicted as standing between to camels ( which is hardly recognizable here but comparable to known authentic examples).
The estimate is based on similar offered or sold at auction. There is no measurement for the sentimental value you might attach to it.