This EarthCache is on Tufton Street, Westminster, London. Due to the urban location, the GPS signal may bounch about, so look for the RED DRY RINSER sign then look above it. It is at 1.70m height. It may take you a while to spot what you are looking for.
This EarthCache is in central London, so if challenged please be honest about what you are doing.
We are here to look for a specific type of fossil - an echinoderm, or more commonly known as a sea urchin.
A fossil is trace or remains of a plant, animal or other organisms. However, there is more to fossilization than just bones, or remains of a T Rex.
There are many EarthCaches which can teach you about the whole process of fossilization, what we are concerned with is this certain type of fossil.
Sea Urchins.
These are small sea bed dweilling organisms that feed on organic matter. They have spines which help to propel themselves along. In our modern era there are about 950 species of sea urchin.
The above diagram is of three views of a sea urchin. In layman's terms, the dorsal view is the upper part of the sea urchin, whilst the ventral view us looking at the bottom of the sea urchin.
The hard shell of a sea urchin is known as a TEST. The test is made up of calcium carbonate, and when alive, the sea urchin would have been covered in spines. The spines attached to the sea urchin at the TUBERCULES, which look like dots when the spines have either dropped off, or been removed.
The test, is actually made up of hard sections, known as plates, in-between each plates is a ambulactrum.
Commonly the sea urchin has its mouth on the bottom aspect, and it's anus on the upper aspect. The area where the anus is, is known as the periproct.
This being an EarthCache, in order to log it, I ask that you answer the above questions. Please send them to me, and do not include them in your log. You can send them to me by using the message facility or email, both of which can be found by looking at my profile.
1. Please describe the fossil, in terms of colour, and features that you see and feel. How does the fossil differ from the other rocks that make up the wall?
2. Using the above diagram, please tell me which features of the sea urchin that you can see.
3. Please measure across its width.