I was wondering too. I found this in Wikipedia:

Halloumi or haloumi is a cheese made from a mixture of goat’s and sheep’s milk, and sometimes also cow’s milk. Its texture is described as squeaky. It has a high melting point and so can easily be fried or grilled, a property that makes it a popular meat substitute. Rennet (mostly vegetarian or microbial) is used to curdle the milk in halloumi production, although no acid-producing bacteria are used in its preparation.