H. Description of the Tekhelet-hillazon in the Baraitha d’Tzitzit

שאין צובעין תכלת אלא בחלזון חלזון למה הוא.

ברייתו דומה לדג וגופו דומה לרקיע ואין עולה אלא שבע שנים

“… What is the hillazon like unto? Its shape is like unto that of a fish and its body (i.e., colour of body or shell) is like unto the sky, and it only ‘comes up’ once in seven years therefore is it very dear?”

The differences to be noted are:

(1) characteristic (b) precedes (a);

(2) the colour is likened to the sky not to the sea as in the Talmud;

(3) the shorter number seven for seventy of the Talmud.