When SCP-003 drops below the temperature of 35°C, both components react.

First, SCP-003-1 enters a growth state characterized by an exponential increase in mass. This growth state consists of two stages. In both stages, SCP-003-1 partially fuels its growth by converting matter around it, starting with any surrounding inorganic material, including atmospheric elements, then nonliving organic material, including cells of dead skin, hair, chitin, enamel, keratin, and other biological materials.

The first stage is always the same. SCP-003-1 will first increase its mass, then take a form similar in shape to an ophiuroid (brittle star) of fifteen meters in diameter (including what appears to be a central processor of three meters in diameter). It will form sensory organs that appear to scan its surrounding environment, and will partially convert the area around it to an unidentified anomalous substance (SCP-003-2 seems immune from conversion).