I wasn’t aware they made a u-shaped pre-cast beam. Usually it is a solid 8"x8" concrete precast reinforced with 4-#4 bars or bigger.
In residential, they usually use a bond beam block for openings and a bondbeam block at the top of the wall for truss ties if necessary.
Bond beam blocks are concrete masonry units that are similar to standard CMUs, except that the webs are cut to remove the upper portion. In many cases, the block units are provided with knock out sections that are removed when the units are used in the bond beam.
The notch in the top of the webs creates a space into which the horizontal reinforcing is placed in a reinforced masonry wall. The vertical reinforcing extends through the cells in the bond beam unit. A wire mesh or fabric is placed in the bed joint just below the bond beam unit at any of the cells that do not contain vertical reinforcing as the walls are erected. This mesh prevents the grout from flowing down the vertical cell space so the horizontal bond beam can be filled without filling all the vertical cells.
Some bondbeams have a solid bottom.
Lintel or channel blocks are U-shaped concrete masonry units used above openings to create lintels. Since lintel block units are solid along the bottom, the underside can be exposed at openings. However, because of this feature, these block units do not allow vertical reinforcement to extend through them.
Therefore, lintel blocks would typically not be used in wall systems that have a combination of vertical and horizontal reinforcement. If lintel blocks are used to create bond beams in walls with vertical reinforcing, a portion of the bottom of the units would need to be removed in order to extend the vertical reinforcing through.
That is why I thought it was precast Concrete.
I also wondered why it was notched at the bearing seat and filled with mortar, which throws all logic aside.