Eukaryotic organisms that decompose dead organisms and absorb nutrients are generally found in the Kingdom Fungi. Fungi play a crucial role in ecosystems by breaking down dead organic matter, which helps recycle nutrients back into the environment. They secrete enzymes that break down complex organic materials into simpler compounds, which they then absorb. This process not only aids in decomposition but also supports the growth of plants and other organisms by enriching the soil with essential nutrients.