Right now the Microstation DGN readers doesn't support Mesh element types. When the reader encounter such a object the following warning is shown in the log: WARN |DESIGN READER: Found element of type '105', which is unrecognized or unsupported. Skipping element
When working with infrastructure projects Microstation is widely used and the mesh element type is as common as butter on a toast.
A question about this topic was asked already in February 2014 here.
(For further reference to Microstation element types, here's a good link)
