Freshwater ostracod/ seed shrimp 
( Small species 0.2cm )
Freshwater ostracods, commonly known as seed shrimp, are tiny crustaceans usually between 0.1 and 0.5 cm found naturally in ponds, ditches, wetlands and other freshwater habitats across the UK. Most measure only around 0.5–3 mm and have a distinctive hard, two-part shell enclosing their body.
Ostracods are useful members of a healthy pond ecosystem, feeding on algae, bacteria, decaying plant material and other organic debris, helping with nutrient recycling and the breakdown of waste. They also provide a valuable natural food source for fish, newts, aquatic insects and other small pond animals, being crustaceans they are an excellent source of calcium for newt larvae, fascinating and completely aquatic, ostracods make an excellent addition to wildlife ponds, natural aquariums and freshwater microhabitats.