Seeds - Seeds are small pieces of XML that tell the Maltego client where it should look (at which servers) for transforms. Seeds can be thought of as something like the index of a book where you can use that to see where the relevant content is located. Seeds are defined within the iTDS and require no manual editing to create these files. You can view an example of creating a seed in the building your own TDS transforms tutorial in the getting started guide.
Adding within Maltego
The "discovery process" is the means in which Maltego discovers transforms and registers them in the client. It works in the following steps:
A seed is added to the Maltego client that points to an XML file like the one listed above
The Maltego client then browses to each of the TransformApplication URL and prepends the text "?Command=_TRANSFORMS" which tells that server to list all the transforms available for that seed
Each of these Transforms is then registered within the client for that particular seed. This includes the display name (listed in the context menu) as well as transform name which is used when running a transform. Transforms can also have additional settings such as transform settings and OAuth configurations.
Seeds are added to your Maltego client from the Transform Hub by clicking on the last transform hub item which is a green plus (+) button as shown below:
After clinking the green plus (+) button the Add Transform Seed window will open as shown below. Here you can add your seed URL as well as other details about the transform seed:
After entering your trasform seed URL and the other fields for the seed you can click "OK" and then "Install" as shown below. The Transforms from this seed will then be installed to your Maltego client.