Algae are usually thought of as a type of aquatic plant or slimy substance. In Latin, the name alga means “seaweed” and yet not every type of algae takes the form of a weed or lives in the sea. Some varieties live in soil and can withstand long periods without water; other live in snow or inside other animal species. Though scientists agree that there are four of algae, each distinguished by different pigmentations, the classification of all but one type remains precarious.