Snowflakes and snow crystals can grow fairly large, but there are

The Guinness World Record folks would have us believe in a 19th century snowflake more than a foot wide, but some scientists are skeptical.

Snowflake Shapes

How snowflakes grow

Crystalline Entities – Snow, Hoarfrost and Rime Ice

Snowflake Science

Visualized: How Snowflakes are Formed

Snowflake Science

Snowflakes and snow crystals

Guide to Snowflakes

The Formation of Snow Crystals

Is it true that no two snowflakes are identical? Office for Science and Society - McGill University

Two snowflakes may actually be alike

Why are all snowflakes unique? - BBC Bitesize

Snow Crystals: A Natural Blend of Science and Art

What makes a snowflake special?, News