Still life component
A still life component is any unstable pattern which can be combined with either existing still lifes or other still life components to create a proper still life.
Induction coils are a notable class of still life components, which require stabilisation from other objects (either other induction coils or self-stable patterns) which are usually detached from them, resulting in an object with multiple islands.
There are other types of components which interact differently with other objects. For example, the tail and nine are "appendage"-like structures which attach to other structures diagonally, and the pre-block, hook and claw are structures which can have objects such as tails attached for mutual stabilisation.
Patterns which are stable by themselves while also accepting components, such as a tub which can be upgraded to a tub with tail, are generally not considered components.
Example
Claw is a still life component featured in all of these still lives:
