Tomato seeds The tomato variety bred for sauce and packaging is known as a plum tomato, commonly referred to as a processing tomato or paste tomato. They often have an oval or cylindrical shape, have much fewer locules (seed chambers) than conventional round tomatoes (typically only two), and generally contain more solids, making them more suited for processing. Due to their reputation as being easier to handle and being available in a more mature stage than other supermarket tomatoes, plum tomatoes are occasionally preferred by chefs for use during the tomato off-season.