Shells are considered biotic because they come from living things. Biotic describes something living or use to be living such as plants and animals. So shells are considered biotic because they come from a living organism.
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Hope that helped:)
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1. A logging company plants two acres of land with
trees for every one acre of forest it removes -B. using resources sustainably-
2. Julia uses old glass jam jars as pots for
her plants-C. recycling resources-
3. Jackson installs a solar-powered water heater
to supply his house with hot water-A. using renewable resources-
