Sponges
Sponges can look like plants, and they are sessile (they fix themselves to rocks or sand, and don't move about). But instead of making their own food like plants do, sponges take their food from water currents that pass through their bodies.
Sponges are an important group of animals. The oldest sponge fossils are over 540 million years old, but we still see sponges alive today. You can find their fossils in England - and parts of Oxfordshire are known for sponges.
All of the sponges on this page are from the Cretaceous period.
Sponges are very simple animals - they have no organs (like a heart) or tissues (like skin).
They have sac-like bodies, and many sponges have skeletons that are made up of small needle-like spicules that are held in their body walls. As adults, they range from a few centimetres to several metres across.
Sponges are aquatic (living in water) and the majority are marine (living in sea).
