The correct answer is Envelope
It's likely to have a Solid Grey color.
The abiotic environment consists of non-living things. So, rocks, temperature and water are part of the abiotic environment.
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate.
