\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{shapes.symbols}
\usetikzlibrary{arrows}
\usetikzlibrary{calc}

\begin{document}

\begin{tikzpicture}[>=stealth]
  \draw [->] (0,0) -- (0,5);
  \draw [->] (0,0) -- (5,0);
  \draw [->] (0,0) -- (0,0,5);

  \node[draw,red,cloud,minimum height=2cm,minimum width=2cm] (mop) at (3,4,3) {$\color{black}\bullet$};

  \node (os) at (2.5,2,3) {object system};
  \draw (os) -- (mop.center);

  \node[red] (mspace) at (5,6,3) {MOP space};
  \draw[red] (mspace) -- (mop);
\end{tikzpicture}

\end{document}