You can use FreeX3D: VRML, X3D, STL viewer by John Alexander Stewart available from Google Play Store:
FreeX3D is a 3D VRML/X3D and STL viewer for Android.
NEW - Anaglyph rendering option for 3D viewing of your 3D files!
FreeX3D allows the user to browse local STL, VRML 97 and X3D files, and to view these files on their Android GLES-2 capable device. You can rotate or zoom STL files; X3D files you can walk, or examine, as defined by the spec. Use one finger to rotate or walk, two to zoom or move in +-Z, depending on navigation mode set.
This version works on Android 2.2 and above. It requires OpenGL ES-2.0, which is available in all modern phones/tablets, and most released over the last couple of years.
There's also an interesting project that worth mentioning, called X3DOM for free on Android devices that support WebGL:
X3DOM (pronounced X-Freedom) is an experimental open source framework and runtime to support the ongoing discussion in the Web3D and W3C communities how an integration of HTML5 and declarative 3D content could look like. It tries to fulfill the current HTML5 specification for declarative 3D content and allows including X3D elements as part of any HTML5 DOM tree.