Snapchat Birthday Emojis are the two different types of emojis, which appear near the usernames of those people, who chose to specify their dates of birth on the app.
Purple Zodiac Emojis:
The first type includes emoji for all the 12 existing Zodiac signs – all of them look like the purple squares with the relative white sign namely:
♈ Aries, which appear near those, born from 21.03 to 20.04;
♉ Taurus, which are for users, born from 21.04 to 21.05;
♊ Gemini, which are for users, born from 22.05 to 21.06;
♋ Cancer, for those, born from 22.06 to 22.07;
♌ Leo emoji, for those, born from 23.07 to 22.08;
♍ Virgo emoji, for users, born from 23.08 to 23.09;
♎ Libra, for users, born from 24.09 to 23.10;
♏ Scorpius emoji, for dates of birth from 24.10 to 22.11;
♐ Sagittarius, for those, born from 21.11 to 21.12;
♑ Capricorn emoji, for users born from 22.12 to 20.01;
♒ Aquarius, for dates of birth from 21.01 to 10.02;
♓ Pisces emoji, for users born from 20.02 to 20.03.
The second type is the birthday cake emoji, which appears near the name of the user, who is having their birthday exactly this day (by the way, the B-Day date may be changed limited number of times, so no one would boast this decoration for the username and harvest congratulations more than once a year).